1 /* $OpenBSD: monitor.c,v 1.228 2021/08/11 05:20:17 djm Exp $ */
2 /*
3 * Copyright 2002 Niels Provos <[email protected]>
4 * Copyright 2002 Markus Friedl <[email protected]>
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
100 #ifdef GSSAPI
101 static Gssctxt *gsscontext = NULL;
102 #endif
103
104 /* Imports */
105 extern ServerOptions options;
106 extern u_int utmp_len;
107 extern struct sshbuf *loginmsg;
108 extern struct sshauthopt *auth_opts; /* XXX move to permanent ssh->authctxt? */
109
110 /* State exported from the child */
111 static struct sshbuf *child_state;
112
113 /* Functions on the monitor that answer unprivileged requests */
114
115 int mm_answer_moduli(struct ssh *, int, struct sshbuf *);
116 int mm_answer_sign(struct ssh *, int, struct sshbuf *);
117 int mm_answer_pwnamallow(struct ssh *, int, struct sshbuf *);
118 int mm_answer_auth2_read_banner(struct ssh *, int, struct sshbuf *);
119 int mm_answer_authserv(struct ssh *, int, struct sshbuf *);
120 int mm_answer_authpassword(struct ssh *, int, struct sshbuf *);
121 int mm_answer_bsdauthquery(struct ssh *, int, struct sshbuf *);
122 int mm_answer_bsdauthrespond(struct ssh *, int, struct sshbuf *);
123 int mm_answer_keyallowed(struct ssh *, int, struct sshbuf *);
124 int mm_answer_keyverify(struct ssh *, int, struct sshbuf *);
125 int mm_answer_pty(struct ssh *, int, struct sshbuf *);
126 int mm_answer_pty_cleanup(struct ssh *, int, struct sshbuf *);
127 int mm_answer_term(struct ssh *, int, struct sshbuf *);
128 int mm_answer_rsa_keyallowed(struct ssh *, int, struct sshbuf *);
129 int mm_answer_rsa_challenge(struct ssh *, int, struct sshbuf *);
130 int mm_answer_rsa_response(struct ssh *, int, struct sshbuf *);
131 int mm_answer_sesskey(struct ssh *, int, struct sshbuf *);
132 int mm_answer_sessid(struct ssh *, int, struct sshbuf *);
133
134 #ifdef USE_PAM
135 int mm_answer_pam_start(struct ssh *, int, struct sshbuf *);
136 int mm_answer_pam_account(struct ssh *, int, struct sshbuf *);
137 int mm_answer_pam_init_ctx(struct ssh *, int, struct sshbuf *);
138 int mm_answer_pam_query(struct ssh *, int, struct sshbuf *);
139 int mm_answer_pam_respond(struct ssh *, int, struct sshbuf *);
140 int mm_answer_pam_free_ctx(struct ssh *, int, struct sshbuf *);
141 #endif
142
143 #ifdef GSSAPI
144 int mm_answer_gss_setup_ctx(struct ssh *, int, struct sshbuf *);
145 int mm_answer_gss_accept_ctx(struct ssh *, int, struct sshbuf *);
146 int mm_answer_gss_userok(struct ssh *, int, struct sshbuf *);
147 int mm_answer_gss_checkmic(struct ssh *, int, struct sshbuf *);
148 #endif
149
150 #ifdef SSH_AUDIT_EVENTS
151 int mm_answer_audit_event(struct ssh *, int, struct sshbuf *);
152 int mm_answer_audit_command(struct ssh *, int, struct sshbuf *);
153 #endif
154
155 static Authctxt *authctxt;
156
157 /* local state for key verify */
158 static u_char *key_blob = NULL;
159 static size_t key_bloblen = 0;
160 static u_int key_blobtype = MM_NOKEY;
161 static struct sshauthopt *key_opts = NULL;
162 static char *hostbased_cuser = NULL;
163 static char *hostbased_chost = NULL;
164 static char *auth_method = "unknown";
165 static char *auth_submethod = NULL;
166 static u_int session_id2_len = 0;
167 static u_char *session_id2 = NULL;
168 static pid_t monitor_child_pid;
169
170 struct mon_table {
171 enum monitor_reqtype type;
172 int flags;
173 int (*f)(struct ssh *, int, struct sshbuf *);
174 };
175
176 #define MON_ISAUTH 0x0004 /* Required for Authentication */
177 #define MON_AUTHDECIDE 0x0008 /* Decides Authentication */
178 #define MON_ONCE 0x0010 /* Disable after calling */
179 #define MON_ALOG 0x0020 /* Log auth attempt without authenticating */
180
181 #define MON_AUTH (MON_ISAUTH|MON_AUTHDECIDE)
182
183 #define MON_PERMIT 0x1000 /* Request is permitted */
184
185 static int monitor_read(struct ssh *, struct monitor *, struct mon_table *,
186 struct mon_table **);
187 static int monitor_read_log(struct monitor *);
188
189 struct mon_table mon_dispatch_proto20[] = {
190 #ifdef WITH_OPENSSL
191 {MONITOR_REQ_MODULI, MON_ONCE, mm_answer_moduli},
192 #endif
193 {MONITOR_REQ_SIGN, MON_ONCE, mm_answer_sign},
194 {MONITOR_REQ_PWNAM, MON_ONCE, mm_answer_pwnamallow},
195 {MONITOR_REQ_AUTHSERV, MON_ONCE, mm_answer_authserv},
196 {MONITOR_REQ_AUTH2_READ_BANNER, MON_ONCE, mm_answer_auth2_read_banner},
197 {MONITOR_REQ_AUTHPASSWORD, MON_AUTH, mm_answer_authpassword},
198 #ifdef USE_PAM
199 {MONITOR_REQ_PAM_START, MON_ONCE, mm_answer_pam_start},
200 {MONITOR_REQ_PAM_ACCOUNT, 0, mm_answer_pam_account},
201 {MONITOR_REQ_PAM_INIT_CTX, MON_ONCE, mm_answer_pam_init_ctx},
202 {MONITOR_REQ_PAM_QUERY, 0, mm_answer_pam_query},
203 {MONITOR_REQ_PAM_RESPOND, MON_ONCE, mm_answer_pam_respond},
204 {MONITOR_REQ_PAM_FREE_CTX, MON_ONCE|MON_AUTHDECIDE, mm_answer_pam_free_ctx},
205 #endif
206 #ifdef SSH_AUDIT_EVENTS
207 {MONITOR_REQ_AUDIT_EVENT, MON_PERMIT, mm_answer_audit_event},
208 #endif
209 #ifdef BSD_AUTH
210 {MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery},
211 {MONITOR_REQ_BSDAUTHRESPOND, MON_AUTH, mm_answer_bsdauthrespond},
212 #endif
213 {MONITOR_REQ_KEYALLOWED, MON_ISAUTH, mm_answer_keyallowed},
214 {MONITOR_REQ_KEYVERIFY, MON_AUTH, mm_answer_keyverify},
215 #ifdef GSSAPI
216 {MONITOR_REQ_GSSSETUP, MON_ISAUTH, mm_answer_gss_setup_ctx},
217 {MONITOR_REQ_GSSSTEP, 0, mm_answer_gss_accept_ctx},
218 {MONITOR_REQ_GSSUSEROK, MON_ONCE|MON_AUTHDECIDE, mm_answer_gss_userok},
219 {MONITOR_REQ_GSSCHECKMIC, MON_ONCE, mm_answer_gss_checkmic},
220 #endif
221 {0, 0, NULL}
222 };
223
224 struct mon_table mon_dispatch_postauth20[] = {
225 #ifdef WITH_OPENSSL
226 {MONITOR_REQ_MODULI, 0, mm_answer_moduli},
227 #endif
228 {MONITOR_REQ_SIGN, 0, mm_answer_sign},
229 {MONITOR_REQ_PTY, 0, mm_answer_pty},
230 {MONITOR_REQ_PTYCLEANUP, 0, mm_answer_pty_cleanup},
231 {MONITOR_REQ_TERM, 0, mm_answer_term},
232 #ifdef SSH_AUDIT_EVENTS
233 {MONITOR_REQ_AUDIT_EVENT, MON_PERMIT, mm_answer_audit_event},
234 {MONITOR_REQ_AUDIT_COMMAND, MON_PERMIT, mm_answer_audit_command},
235 #endif
236 {0, 0, NULL}
237 };
238
239 struct mon_table *mon_dispatch;
240
241 /* Specifies if a certain message is allowed at the moment */
242 static void
monitor_permit(struct mon_table * ent,enum monitor_reqtype type,int permit)243 monitor_permit(struct mon_table *ent, enum monitor_reqtype type, int permit)
244 {
245 while (ent->f != NULL) {
246 if (ent->type == type) {
247 ent->flags &= ~MON_PERMIT;
248 ent->flags |= permit ? MON_PERMIT : 0;
249 return;
250 }
251 ent++;
252 }
253 }
254
255 static void
monitor_permit_authentications(int permit)256 monitor_permit_authentications(int permit)
257 {
258 struct mon_table *ent = mon_dispatch;
259
260 while (ent->f != NULL) {
261 if (ent->flags & MON_AUTH) {
262 ent->flags &= ~MON_PERMIT;
263 ent->flags |= permit ? MON_PERMIT : 0;
264 }
265 ent++;
266 }
267 }
268
269 void
monitor_child_preauth(struct ssh * ssh,struct monitor * pmonitor)270 monitor_child_preauth(struct ssh *ssh, struct monitor *pmonitor)
271 {
272 struct mon_table *ent;
273 int authenticated = 0, partial = 0;
274
275 debug3("preauth child monitor started");
276
277 if (pmonitor->m_recvfd >= 0)
278 close(pmonitor->m_recvfd);
279 if (pmonitor->m_log_sendfd >= 0)
280 close(pmonitor->m_log_sendfd);
281 pmonitor->m_log_sendfd = pmonitor->m_recvfd = -1;
282
283 authctxt = (Authctxt *)ssh->authctxt;
284 memset(authctxt, 0, sizeof(*authctxt));
285 ssh->authctxt = authctxt;
286
287 authctxt->loginmsg = loginmsg;
288
289 mon_dispatch = mon_dispatch_proto20;
290 /* Permit requests for moduli and signatures */
291 monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 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 /* Special handling for multiple required authentications */
305 if (options.num_auth_methods != 0) {
306 if (authenticated &&
307 !auth2_update_methods_lists(authctxt,
308 auth_method, auth_submethod)) {
309 debug3_f("method %s: partial", auth_method);
310 authenticated = 0;
311 partial = 1;
312 }
313 }
314
315 if (authenticated) {
316 if (!(ent->flags & MON_AUTHDECIDE))
317 fatal_f("unexpected authentication from %d",
318 ent->type);
319 if (authctxt->pw->pw_uid == 0 &&
320 !auth_root_allowed(ssh, auth_method))
321 authenticated = 0;
322 #ifdef USE_PAM
323 /* PAM needs to perform account checks after auth */
324 if (options.use_pam && authenticated) {
325 struct sshbuf *m;
326
327 if ((m = sshbuf_new()) == NULL)
328 fatal("%s: sshbuf_new failed",
329 __func__);
330 mm_request_receive_expect(pmonitor->m_sendfd,
331 MONITOR_REQ_PAM_ACCOUNT, m);
332 authenticated = mm_answer_pam_account(
333 ssh, pmonitor->m_sendfd, m);
334 sshbuf_free(m);
335 }
336 #endif
337 }
338 if (ent->flags & (MON_AUTHDECIDE|MON_ALOG)) {
339 auth_log(ssh, authenticated, partial,
340 auth_method, auth_submethod);
341 if (!partial && !authenticated)
342 authctxt->failures++;
343 if (authenticated || partial) {
344 auth2_update_session_info(authctxt,
345 auth_method, auth_submethod);
346 }
347 }
348 }
349
350 if (!authctxt->valid)
351 fatal_f("authenticated invalid user");
352 if (strcmp(auth_method, "unknown") == 0)
353 fatal_f("authentication method name unknown");
354
355 debug_f("user %s authenticated by privileged process", authctxt->user);
356 ssh->authctxt = NULL;
357 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user);
358
359 mm_get_keystate(ssh, pmonitor);
360
361 /* Drain any buffered messages from the child */
362 while (pmonitor->m_log_recvfd != -1 && monitor_read_log(pmonitor) == 0)
363 ;
364
365 if (pmonitor->m_recvfd >= 0)
366 close(pmonitor->m_recvfd);
367 if (pmonitor->m_log_sendfd >= 0)
368 close(pmonitor->m_log_sendfd);
369 pmonitor->m_sendfd = pmonitor->m_log_recvfd = -1;
370 }
371
372 static void
monitor_set_child_handler(pid_t pid)373 monitor_set_child_handler(pid_t pid)
374 {
375 monitor_child_pid = pid;
376 }
377
378 static void
monitor_child_handler(int sig)379 monitor_child_handler(int sig)
380 {
381 kill(monitor_child_pid, sig);
382 }
383
384 void
monitor_child_postauth(struct ssh * ssh,struct monitor * pmonitor)385 monitor_child_postauth(struct ssh *ssh, struct monitor *pmonitor)
386 {
387 close(pmonitor->m_recvfd);
388 pmonitor->m_recvfd = -1;
389
390 monitor_set_child_handler(pmonitor->m_pid);
391 ssh_signal(SIGHUP, &monitor_child_handler);
392 ssh_signal(SIGTERM, &monitor_child_handler);
393 ssh_signal(SIGINT, &monitor_child_handler);
394 #ifdef SIGXFSZ
395 ssh_signal(SIGXFSZ, SIG_IGN);
396 #endif
397
398 mon_dispatch = mon_dispatch_postauth20;
399
400 /* Permit requests for moduli and signatures */
401 monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1);
402 monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1);
403 monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1);
404
405 if (auth_opts->permit_pty_flag) {
406 monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1);
407 monitor_permit(mon_dispatch, MONITOR_REQ_PTYCLEANUP, 1);
408 }
409
410 for (;;)
411 monitor_read(ssh, pmonitor, mon_dispatch, NULL);
412 }
413
414 static int
monitor_read_log(struct monitor * pmonitor)415 monitor_read_log(struct monitor *pmonitor)
416 {
417 struct sshbuf *logmsg;
418 u_int len, level, forced;
419 char *msg;
420 u_char *p;
421 int r;
422
423 if ((logmsg = sshbuf_new()) == NULL)
424 fatal_f("sshbuf_new");
425
426 /* Read length */
427 if ((r = sshbuf_reserve(logmsg, 4, &p)) != 0)
428 fatal_fr(r, "reserve len");
429 if (atomicio(read, pmonitor->m_log_recvfd, p, 4) != 4) {
430 if (errno == EPIPE) {
431 sshbuf_free(logmsg);
432 debug_f("child log fd closed");
433 close(pmonitor->m_log_recvfd);
434 pmonitor->m_log_recvfd = -1;
435 return -1;
436 }
437 fatal_f("log fd read: %s", strerror(errno));
438 }
439 if ((r = sshbuf_get_u32(logmsg, &len)) != 0)
440 fatal_fr(r, "parse len");
441 if (len <= 4 || len > 8192)
442 fatal_f("invalid log message length %u", len);
443
444 /* Read severity, message */
445 sshbuf_reset(logmsg);
446 if ((r = sshbuf_reserve(logmsg, len, &p)) != 0)
447 fatal_fr(r, "reserve msg");
448 if (atomicio(read, pmonitor->m_log_recvfd, p, len) != len)
449 fatal_f("log fd read: %s", strerror(errno));
450 if ((r = sshbuf_get_u32(logmsg, &level)) != 0 ||
451 (r = sshbuf_get_u32(logmsg, &forced)) != 0 ||
452 (r = sshbuf_get_cstring(logmsg, &msg, NULL)) != 0)
453 fatal_fr(r, "parse");
454
455 /* Log it */
456 if (log_level_name(level) == NULL)
457 fatal_f("invalid log level %u (corrupted message?)", level);
458 sshlogdirect(level, forced, "%s [preauth]", msg);
459
460 sshbuf_free(logmsg);
461 free(msg);
462
463 return 0;
464 }
465
466 static int
monitor_read(struct ssh * ssh,struct monitor * pmonitor,struct mon_table * ent,struct mon_table ** pent)467 monitor_read(struct ssh *ssh, struct monitor *pmonitor, struct mon_table *ent,
468 struct mon_table **pent)
469 {
470 struct sshbuf *m;
471 int r, ret;
472 u_char type;
473 struct pollfd pfd[2];
474
475 for (;;) {
476 memset(&pfd, 0, sizeof(pfd));
477 pfd[0].fd = pmonitor->m_sendfd;
478 pfd[0].events = POLLIN;
479 pfd[1].fd = pmonitor->m_log_recvfd;
480 pfd[1].events = pfd[1].fd == -1 ? 0 : POLLIN;
481 if (poll(pfd, pfd[1].fd == -1 ? 1 : 2, -1) == -1) {
482 if (errno == EINTR || errno == EAGAIN)
483 continue;
484 fatal_f("poll: %s", strerror(errno));
485 }
486 if (pfd[1].revents) {
487 /*
488 * Drain all log messages before processing next
489 * monitor request.
490 */
491 monitor_read_log(pmonitor);
492 continue;
493 }
494 if (pfd[0].revents)
495 break; /* Continues below */
496 }
497
498 if ((m = sshbuf_new()) == NULL)
499 fatal_f("sshbuf_new");
500
501 mm_request_receive(pmonitor->m_sendfd, m);
502 if ((r = sshbuf_get_u8(m, &type)) != 0)
503 fatal_fr(r, "parse type");
504
505 debug3_f("checking request %d", type);
506
507 while (ent->f != NULL) {
508 if (ent->type == type)
509 break;
510 ent++;
511 }
512
513 if (ent->f != NULL) {
514 if (!(ent->flags & MON_PERMIT))
515 fatal_f("unpermitted request %d", type);
516 ret = (*ent->f)(ssh, pmonitor->m_sendfd, m);
517 sshbuf_free(m);
518
519 /* The child may use this request only once, disable it */
520 if (ent->flags & MON_ONCE) {
521 debug2_f("%d used once, disabling now", type);
522 ent->flags &= ~MON_PERMIT;
523 }
524
525 if (pent != NULL)
526 *pent = ent;
527
528 return ret;
529 }
530
531 fatal_f("unsupported request: %d", type);
532
533 /* NOTREACHED */
534 return (-1);
535 }
536
537 /* allowed key state */
538 static int
monitor_allowed_key(const u_char * blob,u_int bloblen)539 monitor_allowed_key(const u_char *blob, u_int bloblen)
540 {
541 /* make sure key is allowed */
542 if (key_blob == NULL || key_bloblen != bloblen ||
543 timingsafe_bcmp(key_blob, blob, key_bloblen))
544 return (0);
545 return (1);
546 }
547
548 static void
monitor_reset_key_state(void)549 monitor_reset_key_state(void)
550 {
551 /* reset state */
552 free(key_blob);
553 free(hostbased_cuser);
554 free(hostbased_chost);
555 sshauthopt_free(key_opts);
556 key_blob = NULL;
557 key_bloblen = 0;
558 key_blobtype = MM_NOKEY;
559 key_opts = NULL;
560 hostbased_cuser = NULL;
561 hostbased_chost = NULL;
562 }
563
564 #ifdef WITH_OPENSSL
565 int
mm_answer_moduli(struct ssh * ssh,int sock,struct sshbuf * m)566 mm_answer_moduli(struct ssh *ssh, int sock, struct sshbuf *m)
567 {
568 DH *dh;
569 const BIGNUM *dh_p, *dh_g;
570 int r;
571 u_int min, want, max;
572
573 if ((r = sshbuf_get_u32(m, &min)) != 0 ||
574 (r = sshbuf_get_u32(m, &want)) != 0 ||
575 (r = sshbuf_get_u32(m, &max)) != 0)
576 fatal_fr(r, "parse");
577
578 debug3_f("got parameters: %d %d %d", min, want, max);
579 /* We need to check here, too, in case the child got corrupted */
580 if (max < min || want < min || max < want)
581 fatal_f("bad parameters: %d %d %d", min, want, max);
582
583 sshbuf_reset(m);
584
585 dh = choose_dh(min, want, max);
586 if (dh == NULL) {
587 if ((r = sshbuf_put_u8(m, 0)) != 0)
588 fatal_fr(r, "assemble empty");
589 return (0);
590 } else {
591 /* Send first bignum */
592 DH_get0_pqg(dh, &dh_p, NULL, &dh_g);
593 if ((r = sshbuf_put_u8(m, 1)) != 0 ||
594 (r = sshbuf_put_bignum2(m, dh_p)) != 0 ||
595 (r = sshbuf_put_bignum2(m, dh_g)) != 0)
596 fatal_fr(r, "assemble");
597
598 DH_free(dh);
599 }
600 mm_request_send(sock, MONITOR_ANS_MODULI, m);
601 return (0);
602 }
603 #endif
604
605 int
mm_answer_sign(struct ssh * ssh,int sock,struct sshbuf * m)606 mm_answer_sign(struct ssh *ssh, int sock, struct sshbuf *m)
607 {
608 extern int auth_sock; /* XXX move to state struct? */
609 struct sshkey *key;
610 struct sshbuf *sigbuf = NULL;
611 u_char *p = NULL, *signature = NULL;
612 char *alg = NULL;
613 size_t datlen, siglen, alglen;
614 int r, is_proof = 0;
615 u_int keyid, compat;
616 const char proof_req[] = "[email protected]";
617
618 debug3_f("entering");
619
620 if ((r = sshbuf_get_u32(m, &keyid)) != 0 ||
621 (r = sshbuf_get_string(m, &p, &datlen)) != 0 ||
622 (r = sshbuf_get_cstring(m, &alg, &alglen)) != 0 ||
623 (r = sshbuf_get_u32(m, &compat)) != 0)
624 fatal_fr(r, "parse");
625 if (keyid > INT_MAX)
626 fatal_f("invalid key ID");
627
628 /*
629 * Supported KEX types use SHA1 (20 bytes), SHA256 (32 bytes),
630 * SHA384 (48 bytes) and SHA512 (64 bytes).
631 *
632 * Otherwise, verify the signature request is for a hostkey
633 * proof.
634 *
635 * XXX perform similar check for KEX signature requests too?
636 * it's not trivial, since what is signed is the hash, rather
637 * than the full kex structure...
638 */
639 if (datlen != 20 && datlen != 32 && datlen != 48 && datlen != 64) {
640 /*
641 * Construct expected hostkey proof and compare it to what
642 * the client sent us.
643 */
644 if (session_id2_len == 0) /* hostkeys is never first */
645 fatal_f("bad data length: %zu", datlen);
646 if ((key = get_hostkey_public_by_index(keyid, ssh)) == NULL)
647 fatal_f("no hostkey for index %d", keyid);
648 if ((sigbuf = sshbuf_new()) == NULL)
649 fatal_f("sshbuf_new");
650 if ((r = sshbuf_put_cstring(sigbuf, proof_req)) != 0 ||
651 (r = sshbuf_put_string(sigbuf, session_id2,
652 session_id2_len)) != 0 ||
653 (r = sshkey_puts(key, sigbuf)) != 0)
654 fatal_fr(r, "assemble private key proof");
655 if (datlen != sshbuf_len(sigbuf) ||
656 memcmp(p, sshbuf_ptr(sigbuf), sshbuf_len(sigbuf)) != 0)
657 fatal_f("bad data length: %zu, hostkey proof len %zu",
658 datlen, sshbuf_len(sigbuf));
659 sshbuf_free(sigbuf);
660 is_proof = 1;
661 }
662
663 /* save session id, it will be passed on the first call */
664 if (session_id2_len == 0) {
665 session_id2_len = datlen;
666 session_id2 = xmalloc(session_id2_len);
667 memcpy(session_id2, p, session_id2_len);
668 }
669
670 if ((key = get_hostkey_by_index(keyid)) != NULL) {
671 if ((r = sshkey_sign(key, &signature, &siglen, p, datlen, alg,
672 options.sk_provider, NULL, compat)) != 0)
673 fatal_fr(r, "sign");
674 } else if ((key = get_hostkey_public_by_index(keyid, ssh)) != NULL &&
675 auth_sock > 0) {
676 if ((r = ssh_agent_sign(auth_sock, key, &signature, &siglen,
677 p, datlen, alg, compat)) != 0)
678 fatal_fr(r, "agent sign");
679 } else
680 fatal_f("no hostkey from index %d", keyid);
681
682 debug3_f("%s %s signature len=%zu", alg,
683 is_proof ? "hostkey proof" : "KEX", siglen);
684
685 sshbuf_reset(m);
686 if ((r = sshbuf_put_string(m, signature, siglen)) != 0)
687 fatal_fr(r, "assemble");
688
689 free(alg);
690 free(p);
691 free(signature);
692
693 mm_request_send(sock, MONITOR_ANS_SIGN, m);
694
695 /* Turn on permissions for getpwnam */
696 monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1);
697
698 return (0);
699 }
700
701 #define PUTPW(b, id) \
702 do { \
703 if ((r = sshbuf_put_string(b, \
704 &pwent->id, sizeof(pwent->id))) != 0) \
705 fatal_fr(r, "assemble %s", #id); \
706 } while (0)
707
708 /* Retrieves the password entry and also checks if the user is permitted */
709 int
mm_answer_pwnamallow(struct ssh * ssh,int sock,struct sshbuf * m)710 mm_answer_pwnamallow(struct ssh *ssh, int sock, struct sshbuf *m)
711 {
712 char *username;
713 struct passwd *pwent;
714 int r, allowed = 0;
715 u_int i;
716
717 debug3_f("entering");
718
719 if (authctxt->attempt++ != 0)
720 fatal_f("multiple attempts for getpwnam");
721
722 if ((r = sshbuf_get_cstring(m, &username, NULL)) != 0)
723 fatal_fr(r, "parse");
724
725 pwent = getpwnamallow(ssh, username);
726
727 authctxt->user = xstrdup(username);
728 setproctitle("%s [priv]", pwent ? username : "unknown");
729 free(username);
730
731 sshbuf_reset(m);
732
733 if (pwent == NULL) {
734 if ((r = sshbuf_put_u8(m, 0)) != 0)
735 fatal_fr(r, "assemble fakepw");
736 authctxt->pw = fakepw();
737 goto out;
738 }
739
740 allowed = 1;
741 authctxt->pw = pwent;
742 authctxt->valid = 1;
743
744 /* XXX send fake class/dir/shell, etc. */
745 if ((r = sshbuf_put_u8(m, 1)) != 0)
746 fatal_fr(r, "assemble ok");
747 PUTPW(m, pw_uid);
748 PUTPW(m, pw_gid);
749 #ifdef HAVE_STRUCT_PASSWD_PW_CHANGE
750 PUTPW(m, pw_change);
751 #endif
752 #ifdef HAVE_STRUCT_PASSWD_PW_EXPIRE
753 PUTPW(m, pw_expire);
754 #endif
755 if ((r = sshbuf_put_cstring(m, pwent->pw_name)) != 0 ||
756 (r = sshbuf_put_cstring(m, "*")) != 0 ||
757 #ifdef HAVE_STRUCT_PASSWD_PW_GECOS
758 (r = sshbuf_put_cstring(m, pwent->pw_gecos)) != 0 ||
759 #endif
760 #ifdef HAVE_STRUCT_PASSWD_PW_CLASS
761 (r = sshbuf_put_cstring(m, pwent->pw_class)) != 0 ||
762 #endif
763 (r = sshbuf_put_cstring(m, pwent->pw_dir)) != 0 ||
764 (r = sshbuf_put_cstring(m, pwent->pw_shell)) != 0)
765 fatal_fr(r, "assemble pw");
766
767 out:
768 ssh_packet_set_log_preamble(ssh, "%suser %s",
769 authctxt->valid ? "authenticating" : "invalid ", authctxt->user);
770 if ((r = sshbuf_put_string(m, &options, sizeof(options))) != 0)
771 fatal_fr(r, "assemble options");
772
773 #define M_CP_STROPT(x) do { \
774 if (options.x != NULL && \
775 (r = sshbuf_put_cstring(m, options.x)) != 0) \
776 fatal_fr(r, "assemble %s", #x); \
777 } while (0)
778 #define M_CP_STRARRAYOPT(x, nx) do { \
779 for (i = 0; i < options.nx; i++) { \
780 if ((r = sshbuf_put_cstring(m, options.x[i])) != 0) \
781 fatal_fr(r, "assemble %s", #x); \
782 } \
783 } while (0)
784 /* See comment in servconf.h */
785 COPY_MATCH_STRING_OPTS();
786 #undef M_CP_STROPT
787 #undef M_CP_STRARRAYOPT
788
789 /* Create valid auth method lists */
790 if (auth2_setup_methods_lists(authctxt) != 0) {
791 /*
792 * The monitor will continue long enough to let the child
793 * run to it's packet_disconnect(), but it must not allow any
794 * authentication to succeed.
795 */
796 debug_f("no valid authentication method lists");
797 }
798
799 debug3_f("sending MONITOR_ANS_PWNAM: %d", allowed);
800 mm_request_send(sock, MONITOR_ANS_PWNAM, m);
801
802 /* Allow service/style information on the auth context */
803 monitor_permit(mon_dispatch, MONITOR_REQ_AUTHSERV, 1);
804 monitor_permit(mon_dispatch, MONITOR_REQ_AUTH2_READ_BANNER, 1);
805
806 #ifdef USE_PAM
807 if (options.use_pam)
808 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_START, 1);
809 #endif
810
811 return (0);
812 }
813
mm_answer_auth2_read_banner(struct ssh * ssh,int sock,struct sshbuf * m)814 int mm_answer_auth2_read_banner(struct ssh *ssh, int sock, struct sshbuf *m)
815 {
816 char *banner;
817 int r;
818
819 sshbuf_reset(m);
820 banner = auth2_read_banner();
821 if ((r = sshbuf_put_cstring(m, banner != NULL ? banner : "")) != 0)
822 fatal_fr(r, "assemble");
823 mm_request_send(sock, MONITOR_ANS_AUTH2_READ_BANNER, m);
824 free(banner);
825
826 return (0);
827 }
828
829 int
mm_answer_authserv(struct ssh * ssh,int sock,struct sshbuf * m)830 mm_answer_authserv(struct ssh *ssh, int sock, struct sshbuf *m)
831 {
832 int r;
833
834 monitor_permit_authentications(1);
835
836 if ((r = sshbuf_get_cstring(m, &authctxt->service, NULL)) != 0 ||
837 (r = sshbuf_get_cstring(m, &authctxt->style, NULL)) != 0)
838 fatal_fr(r, "parse");
839 debug3_f("service=%s, style=%s", authctxt->service, authctxt->style);
840
841 if (strlen(authctxt->style) == 0) {
842 free(authctxt->style);
843 authctxt->style = NULL;
844 }
845
846 return (0);
847 }
848
849 /*
850 * Check that the key type appears in the supplied pattern list, ignoring
851 * mismatches in the signature algorithm. (Signature algorithm checks are
852 * performed in the unprivileged authentication code).
853 * Returns 1 on success, 0 otherwise.
854 */
855 static int
key_base_type_match(const char * method,const struct sshkey * key,const char * list)856 key_base_type_match(const char *method, const struct sshkey *key,
857 const char *list)
858 {
859 char *s, *l, *ol = xstrdup(list);
860 int found = 0;
861
862 l = ol;
863 for ((s = strsep(&l, ",")); s && *s != '\0'; (s = strsep(&l, ","))) {
864 if (sshkey_type_from_name(s) == key->type) {
865 found = 1;
866 break;
867 }
868 }
869 if (!found) {
870 error("%s key type %s is not in permitted list %s", method,
871 sshkey_ssh_name(key), list);
872 }
873
874 free(ol);
875 return found;
876 }
877
878 int
mm_answer_authpassword(struct ssh * ssh,int sock,struct sshbuf * m)879 mm_answer_authpassword(struct ssh *ssh, int sock, struct sshbuf *m)
880 {
881 static int call_count;
882 char *passwd;
883 int r, authenticated;
884 size_t plen;
885
886 if (!options.password_authentication)
887 fatal_f("password authentication not enabled");
888 if ((r = sshbuf_get_cstring(m, &passwd, &plen)) != 0)
889 fatal_fr(r, "parse");
890 /* Only authenticate if the context is valid */
891 authenticated = options.password_authentication &&
892 auth_password(ssh, passwd);
893 freezero(passwd, plen);
894
895 sshbuf_reset(m);
896 if ((r = sshbuf_put_u32(m, authenticated)) != 0)
897 fatal_fr(r, "assemble");
898 #ifdef USE_PAM
899 if ((r = sshbuf_put_u32(m, sshpam_get_maxtries_reached())) != 0)
900 fatal_fr(r, "assemble PAM");
901 #endif
902
903 debug3("%s: sending result %d", __func__, authenticated);
904 debug3_f("sending result %d", authenticated);
905 mm_request_send(sock, MONITOR_ANS_AUTHPASSWORD, m);
906
907 call_count++;
908 if (plen == 0 && call_count == 1)
909 auth_method = "none";
910 else
911 auth_method = "password";
912
913 /* Causes monitor loop to terminate if authenticated */
914 return (authenticated);
915 }
916
917 #ifdef BSD_AUTH
918 int
mm_answer_bsdauthquery(struct ssh * ssh,int sock,struct sshbuf * m)919 mm_answer_bsdauthquery(struct ssh *ssh, int sock, struct sshbuf *m)
920 {
921 char *name, *infotxt;
922 u_int numprompts, *echo_on, success;
923 char **prompts;
924 int r;
925
926 if (!options.kbd_interactive_authentication)
927 fatal_f("kbd-int authentication not enabled");
928 success = bsdauth_query(authctxt, &name, &infotxt, &numprompts,
929 &prompts, &echo_on) < 0 ? 0 : 1;
930
931 sshbuf_reset(m);
932 if ((r = sshbuf_put_u32(m, success)) != 0)
933 fatal_fr(r, "assemble");
934 if (success) {
935 if ((r = sshbuf_put_cstring(m, prompts[0])) != 0)
936 fatal_fr(r, "assemble prompt");
937 }
938
939 debug3_f("sending challenge success: %u", success);
940 mm_request_send(sock, MONITOR_ANS_BSDAUTHQUERY, m);
941
942 if (success) {
943 free(name);
944 free(infotxt);
945 free(prompts);
946 free(echo_on);
947 }
948
949 return (0);
950 }
951
952 int
mm_answer_bsdauthrespond(struct ssh * ssh,int sock,struct sshbuf * m)953 mm_answer_bsdauthrespond(struct ssh *ssh, int sock, struct sshbuf *m)
954 {
955 char *response;
956 int r, authok;
957
958 if (!options.kbd_interactive_authentication)
959 fatal_f("kbd-int authentication not enabled");
960 if (authctxt->as == NULL)
961 fatal_f("no bsd auth session");
962
963 if ((r = sshbuf_get_cstring(m, &response, NULL)) != 0)
964 fatal_fr(r, "parse");
965 authok = options.kbd_interactive_authentication &&
966 auth_userresponse(authctxt->as, response, 0);
967 authctxt->as = NULL;
968 debug3_f("<%s> = <%d>", response, authok);
969 free(response);
970
971 sshbuf_reset(m);
972 if ((r = sshbuf_put_u32(m, authok)) != 0)
973 fatal_fr(r, "assemble");
974
975 debug3_f("sending authenticated: %d", authok);
976 mm_request_send(sock, MONITOR_ANS_BSDAUTHRESPOND, m);
977
978 auth_method = "keyboard-interactive";
979 auth_submethod = "bsdauth";
980
981 return (authok != 0);
982 }
983 #endif
984
985 #ifdef USE_PAM
986 int
mm_answer_pam_start(struct ssh * ssh,int sock,struct sshbuf * m)987 mm_answer_pam_start(struct ssh *ssh, int sock, struct sshbuf *m)
988 {
989 if (!options.use_pam)
990 fatal("UsePAM not set, but ended up in %s anyway", __func__);
991
992 start_pam(ssh);
993
994 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_ACCOUNT, 1);
995 if (options.kbd_interactive_authentication)
996 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_INIT_CTX, 1);
997
998 return (0);
999 }
1000
1001 int
mm_answer_pam_account(struct ssh * ssh,int sock,struct sshbuf * m)1002 mm_answer_pam_account(struct ssh *ssh, int sock, struct sshbuf *m)
1003 {
1004 u_int ret;
1005 int r;
1006
1007 if (!options.use_pam)
1008 fatal("%s: PAM not enabled", __func__);
1009
1010 ret = do_pam_account();
1011
1012 if ((r = sshbuf_put_u32(m, ret)) != 0 ||
1013 (r = sshbuf_put_stringb(m, loginmsg)) != 0)
1014 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1015
1016 mm_request_send(sock, MONITOR_ANS_PAM_ACCOUNT, m);
1017
1018 return (ret);
1019 }
1020
1021 static void *sshpam_ctxt, *sshpam_authok;
1022 extern KbdintDevice sshpam_device;
1023
1024 int
mm_answer_pam_init_ctx(struct ssh * ssh,int sock,struct sshbuf * m)1025 mm_answer_pam_init_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
1026 {
1027 u_int ok = 0;
1028 int r;
1029
1030 debug3("%s", __func__);
1031 if (!options.kbd_interactive_authentication)
1032 fatal("%s: kbd-int authentication not enabled", __func__);
1033 if (sshpam_ctxt != NULL)
1034 fatal("%s: already called", __func__);
1035 sshpam_ctxt = (sshpam_device.init_ctx)(authctxt);
1036 sshpam_authok = NULL;
1037 sshbuf_reset(m);
1038 if (sshpam_ctxt != NULL) {
1039 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_FREE_CTX, 1);
1040 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_QUERY, 1);
1041 ok = 1;
1042 }
1043 if ((r = sshbuf_put_u32(m, ok)) != 0)
1044 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1045 mm_request_send(sock, MONITOR_ANS_PAM_INIT_CTX, m);
1046 return (0);
1047 }
1048
1049 int
mm_answer_pam_query(struct ssh * ssh,int sock,struct sshbuf * m)1050 mm_answer_pam_query(struct ssh *ssh, int sock, struct sshbuf *m)
1051 {
1052 char *name = NULL, *info = NULL, **prompts = NULL;
1053 u_int i, num = 0, *echo_on = 0;
1054 int r, ret;
1055
1056 debug3("%s", __func__);
1057 sshpam_authok = NULL;
1058 if (sshpam_ctxt == NULL)
1059 fatal("%s: no context", __func__);
1060 ret = (sshpam_device.query)(sshpam_ctxt, &name, &info,
1061 &num, &prompts, &echo_on);
1062 if (ret == 0 && num == 0)
1063 sshpam_authok = sshpam_ctxt;
1064 if (num > 1 || name == NULL || info == NULL)
1065 fatal("sshpam_device.query failed");
1066 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_RESPOND, 1);
1067 sshbuf_reset(m);
1068 if ((r = sshbuf_put_u32(m, ret)) != 0 ||
1069 (r = sshbuf_put_cstring(m, name)) != 0 ||
1070 (r = sshbuf_put_cstring(m, info)) != 0 ||
1071 (r = sshbuf_put_u32(m, sshpam_get_maxtries_reached())) != 0 ||
1072 (r = sshbuf_put_u32(m, num)) != 0)
1073 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1074 free(name);
1075 free(info);
1076 for (i = 0; i < num; ++i) {
1077 if ((r = sshbuf_put_cstring(m, prompts[i])) != 0 ||
1078 (r = sshbuf_put_u32(m, echo_on[i])) != 0)
1079 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1080 free(prompts[i]);
1081 }
1082 free(prompts);
1083 free(echo_on);
1084 auth_method = "keyboard-interactive";
1085 auth_submethod = "pam";
1086 mm_request_send(sock, MONITOR_ANS_PAM_QUERY, m);
1087 return (0);
1088 }
1089
1090 int
mm_answer_pam_respond(struct ssh * ssh,int sock,struct sshbuf * m)1091 mm_answer_pam_respond(struct ssh *ssh, int sock, struct sshbuf *m)
1092 {
1093 char **resp;
1094 u_int i, num;
1095 int r, ret;
1096
1097 debug3("%s", __func__);
1098 if (sshpam_ctxt == NULL)
1099 fatal("%s: no context", __func__);
1100 sshpam_authok = NULL;
1101 if ((r = sshbuf_get_u32(m, &num)) != 0)
1102 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1103 if (num > 0) {
1104 resp = xcalloc(num, sizeof(char *));
1105 for (i = 0; i < num; ++i) {
1106 if ((r = sshbuf_get_cstring(m, &(resp[i]), NULL)) != 0)
1107 fatal("%s: buffer error: %s",
1108 __func__, ssh_err(r));
1109 }
1110 ret = (sshpam_device.respond)(sshpam_ctxt, num, resp);
1111 for (i = 0; i < num; ++i)
1112 free(resp[i]);
1113 free(resp);
1114 } else {
1115 ret = (sshpam_device.respond)(sshpam_ctxt, num, NULL);
1116 }
1117 sshbuf_reset(m);
1118 if ((r = sshbuf_put_u32(m, ret)) != 0)
1119 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1120 mm_request_send(sock, MONITOR_ANS_PAM_RESPOND, m);
1121 auth_method = "keyboard-interactive";
1122 auth_submethod = "pam";
1123 if (ret == 0)
1124 sshpam_authok = sshpam_ctxt;
1125 return (0);
1126 }
1127
1128 int
mm_answer_pam_free_ctx(struct ssh * ssh,int sock,struct sshbuf * m)1129 mm_answer_pam_free_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
1130 {
1131 int r = sshpam_authok != NULL && sshpam_authok == sshpam_ctxt;
1132
1133 debug3("%s", __func__);
1134 if (sshpam_ctxt == NULL)
1135 fatal("%s: no context", __func__);
1136 (sshpam_device.free_ctx)(sshpam_ctxt);
1137 sshpam_ctxt = sshpam_authok = NULL;
1138 sshbuf_reset(m);
1139 mm_request_send(sock, MONITOR_ANS_PAM_FREE_CTX, m);
1140 /* Allow another attempt */
1141 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_INIT_CTX, 1);
1142 auth_method = "keyboard-interactive";
1143 auth_submethod = "pam";
1144 return r;
1145 }
1146 #endif
1147
1148 int
mm_answer_keyallowed(struct ssh * ssh,int sock,struct sshbuf * m)1149 mm_answer_keyallowed(struct ssh *ssh, int sock, struct sshbuf *m)
1150 {
1151 struct sshkey *key = NULL;
1152 char *cuser, *chost;
1153 u_int pubkey_auth_attempt;
1154 u_int type = 0;
1155 int r, allowed = 0;
1156 struct sshauthopt *opts = NULL;
1157
1158 debug3_f("entering");
1159 if ((r = sshbuf_get_u32(m, &type)) != 0 ||
1160 (r = sshbuf_get_cstring(m, &cuser, NULL)) != 0 ||
1161 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 ||
1162 (r = sshkey_froms(m, &key)) != 0 ||
1163 (r = sshbuf_get_u32(m, &pubkey_auth_attempt)) != 0)
1164 fatal_fr(r, "parse");
1165
1166 if (key != NULL && authctxt->valid) {
1167 /* These should not make it past the privsep child */
1168 if (sshkey_type_plain(key->type) == KEY_RSA &&
1169 (ssh->compat & SSH_BUG_RSASIGMD5) != 0)
1170 fatal_f("passed a SSH_BUG_RSASIGMD5 key");
1171
1172 switch (type) {
1173 case MM_USERKEY:
1174 auth_method = "publickey";
1175 if (!options.pubkey_authentication)
1176 break;
1177 if (auth2_key_already_used(authctxt, key))
1178 break;
1179 if (!key_base_type_match(auth_method, key,
1180 options.pubkey_accepted_algos))
1181 break;
1182 allowed = user_key_allowed(ssh, authctxt->pw, key,
1183 pubkey_auth_attempt, &opts);
1184 break;
1185 case MM_HOSTKEY:
1186 auth_method = "hostbased";
1187 if (!options.hostbased_authentication)
1188 break;
1189 if (auth2_key_already_used(authctxt, key))
1190 break;
1191 if (!key_base_type_match(auth_method, key,
1192 options.hostbased_accepted_algos))
1193 break;
1194 allowed = hostbased_key_allowed(ssh, authctxt->pw,
1195 cuser, chost, key);
1196 auth2_record_info(authctxt,
1197 "client user \"%.100s\", client host \"%.100s\"",
1198 cuser, chost);
1199 break;
1200 default:
1201 fatal_f("unknown key type %u", type);
1202 break;
1203 }
1204 }
1205
1206 debug3_f("%s authentication%s: %s key is %s", auth_method,
1207 pubkey_auth_attempt ? "" : " test",
1208 (key == NULL || !authctxt->valid) ? "invalid" : sshkey_type(key),
1209 allowed ? "allowed" : "not allowed");
1210
1211 auth2_record_key(authctxt, 0, key);
1212
1213 /* clear temporarily storage (used by verify) */
1214 monitor_reset_key_state();
1215
1216 if (allowed) {
1217 /* Save temporarily for comparison in verify */
1218 if ((r = sshkey_to_blob(key, &key_blob, &key_bloblen)) != 0)
1219 fatal_fr(r, "sshkey_to_blob");
1220 key_blobtype = type;
1221 key_opts = opts;
1222 hostbased_cuser = cuser;
1223 hostbased_chost = chost;
1224 } else {
1225 /* Log failed attempt */
1226 auth_log(ssh, 0, 0, auth_method, NULL);
1227 free(cuser);
1228 free(chost);
1229 }
1230 sshkey_free(key);
1231
1232 sshbuf_reset(m);
1233 if ((r = sshbuf_put_u32(m, allowed)) != 0)
1234 fatal_fr(r, "assemble");
1235 if (opts != NULL && (r = sshauthopt_serialise(opts, m, 1)) != 0)
1236 fatal_fr(r, "sshauthopt_serialise");
1237 mm_request_send(sock, MONITOR_ANS_KEYALLOWED, m);
1238
1239 if (!allowed)
1240 sshauthopt_free(opts);
1241
1242 return (0);
1243 }
1244
1245 static int
monitor_valid_userblob(struct ssh * ssh,const u_char * data,u_int datalen)1246 monitor_valid_userblob(struct ssh *ssh, const u_char *data, u_int datalen)
1247 {
1248 struct sshbuf *b;
1249 const u_char *p;
1250 char *userstyle, *cp;
1251 size_t len;
1252 u_char type;
1253 int r, fail = 0;
1254
1255 if ((b = sshbuf_from(data, datalen)) == NULL)
1256 fatal_f("sshbuf_from");
1257
1258 if (ssh->compat & SSH_OLD_SESSIONID) {
1259 p = sshbuf_ptr(b);
1260 len = sshbuf_len(b);
1261 if ((session_id2 == NULL) ||
1262 (len < session_id2_len) ||
1263 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0))
1264 fail++;
1265 if ((r = sshbuf_consume(b, session_id2_len)) != 0)
1266 fatal_fr(r, "consume");
1267 } else {
1268 if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0)
1269 fatal_fr(r, "parse sessionid");
1270 if ((session_id2 == NULL) ||
1271 (len != session_id2_len) ||
1272 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0))
1273 fail++;
1274 }
1275 if ((r = sshbuf_get_u8(b, &type)) != 0)
1276 fatal_fr(r, "parse type");
1277 if (type != SSH2_MSG_USERAUTH_REQUEST)
1278 fail++;
1279 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1280 fatal_fr(r, "parse userstyle");
1281 xasprintf(&userstyle, "%s%s%s", authctxt->user,
1282 authctxt->style ? ":" : "",
1283 authctxt->style ? authctxt->style : "");
1284 if (strcmp(userstyle, cp) != 0) {
1285 logit("wrong user name passed to monitor: "
1286 "expected %s != %.100s", userstyle, cp);
1287 fail++;
1288 }
1289 free(userstyle);
1290 free(cp);
1291 if ((r = sshbuf_skip_string(b)) != 0 || /* service */
1292 (r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1293 fatal_fr(r, "parse method");
1294 if (strcmp("publickey", cp) != 0)
1295 fail++;
1296 free(cp);
1297 if ((r = sshbuf_get_u8(b, &type)) != 0)
1298 fatal_fr(r, "parse pktype");
1299 if (type == 0)
1300 fail++;
1301 if ((r = sshbuf_skip_string(b)) != 0 || /* pkalg */
1302 (r = sshbuf_skip_string(b)) != 0) /* pkblob */
1303 fatal_fr(r, "parse pk");
1304 if (sshbuf_len(b) != 0)
1305 fail++;
1306 sshbuf_free(b);
1307 return (fail == 0);
1308 }
1309
1310 static int
monitor_valid_hostbasedblob(const u_char * data,u_int datalen,const char * cuser,const char * chost)1311 monitor_valid_hostbasedblob(const u_char *data, u_int datalen,
1312 const char *cuser, const char *chost)
1313 {
1314 struct sshbuf *b;
1315 const u_char *p;
1316 char *cp, *userstyle;
1317 size_t len;
1318 int r, fail = 0;
1319 u_char type;
1320
1321 if ((b = sshbuf_from(data, datalen)) == NULL)
1322 fatal_f("sshbuf_new");
1323 if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0)
1324 fatal_fr(r, "parse sessionid");
1325
1326 if ((session_id2 == NULL) ||
1327 (len != session_id2_len) ||
1328 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0))
1329 fail++;
1330
1331 if ((r = sshbuf_get_u8(b, &type)) != 0)
1332 fatal_fr(r, "parse type");
1333 if (type != SSH2_MSG_USERAUTH_REQUEST)
1334 fail++;
1335 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1336 fatal_fr(r, "parse userstyle");
1337 xasprintf(&userstyle, "%s%s%s", authctxt->user,
1338 authctxt->style ? ":" : "",
1339 authctxt->style ? authctxt->style : "");
1340 if (strcmp(userstyle, cp) != 0) {
1341 logit("wrong user name passed to monitor: "
1342 "expected %s != %.100s", userstyle, cp);
1343 fail++;
1344 }
1345 free(userstyle);
1346 free(cp);
1347 if ((r = sshbuf_skip_string(b)) != 0 || /* service */
1348 (r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1349 fatal_fr(r, "parse method");
1350 if (strcmp(cp, "hostbased") != 0)
1351 fail++;
1352 free(cp);
1353 if ((r = sshbuf_skip_string(b)) != 0 || /* pkalg */
1354 (r = sshbuf_skip_string(b)) != 0) /* pkblob */
1355 fatal_fr(r, "parse pk");
1356
1357 /* verify client host, strip trailing dot if necessary */
1358 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1359 fatal_fr(r, "parse host");
1360 if (((len = strlen(cp)) > 0) && cp[len - 1] == '.')
1361 cp[len - 1] = '\0';
1362 if (strcmp(cp, chost) != 0)
1363 fail++;
1364 free(cp);
1365
1366 /* verify client user */
1367 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0)
1368 fatal_fr(r, "parse ruser");
1369 if (strcmp(cp, cuser) != 0)
1370 fail++;
1371 free(cp);
1372
1373 if (sshbuf_len(b) != 0)
1374 fail++;
1375 sshbuf_free(b);
1376 return (fail == 0);
1377 }
1378
1379 int
mm_answer_keyverify(struct ssh * ssh,int sock,struct sshbuf * m)1380 mm_answer_keyverify(struct ssh *ssh, int sock, struct sshbuf *m)
1381 {
1382 struct sshkey *key;
1383 const u_char *signature, *data, *blob;
1384 char *sigalg = NULL, *fp = NULL;
1385 size_t signaturelen, datalen, bloblen;
1386 int r, ret, req_presence = 0, req_verify = 0, valid_data = 0;
1387 int encoded_ret;
1388 struct sshkey_sig_details *sig_details = NULL;
1389
1390 if ((r = sshbuf_get_string_direct(m, &blob, &bloblen)) != 0 ||
1391 (r = sshbuf_get_string_direct(m, &signature, &signaturelen)) != 0 ||
1392 (r = sshbuf_get_string_direct(m, &data, &datalen)) != 0 ||
1393 (r = sshbuf_get_cstring(m, &sigalg, NULL)) != 0)
1394 fatal_fr(r, "parse");
1395
1396 if (hostbased_cuser == NULL || hostbased_chost == NULL ||
1397 !monitor_allowed_key(blob, bloblen))
1398 fatal_f("bad key, not previously allowed");
1399
1400 /* Empty signature algorithm means NULL. */
1401 if (*sigalg == '\0') {
1402 free(sigalg);
1403 sigalg = NULL;
1404 }
1405
1406 /* XXX use sshkey_froms here; need to change key_blob, etc. */
1407 if ((r = sshkey_from_blob(blob, bloblen, &key)) != 0)
1408 fatal_fr(r, "parse key");
1409
1410 switch (key_blobtype) {
1411 case MM_USERKEY:
1412 valid_data = monitor_valid_userblob(ssh, data, datalen);
1413 auth_method = "publickey";
1414 break;
1415 case MM_HOSTKEY:
1416 valid_data = monitor_valid_hostbasedblob(data, datalen,
1417 hostbased_cuser, hostbased_chost);
1418 auth_method = "hostbased";
1419 break;
1420 default:
1421 valid_data = 0;
1422 break;
1423 }
1424 if (!valid_data)
1425 fatal_f("bad %s signature data blob",
1426 key_blobtype == MM_USERKEY ? "userkey" :
1427 (key_blobtype == MM_HOSTKEY ? "hostkey" : "unknown"));
1428
1429 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash,
1430 SSH_FP_DEFAULT)) == NULL)
1431 fatal_f("sshkey_fingerprint failed");
1432
1433 ret = sshkey_verify(key, signature, signaturelen, data, datalen,
1434 sigalg, ssh->compat, &sig_details);
1435 debug3_f("%s %s signature %s%s%s", auth_method, sshkey_type(key),
1436 (ret == 0) ? "verified" : "unverified",
1437 (ret != 0) ? ": " : "", (ret != 0) ? ssh_err(ret) : "");
1438
1439 if (ret == 0 && key_blobtype == MM_USERKEY && sig_details != NULL) {
1440 req_presence = (options.pubkey_auth_options &
1441 PUBKEYAUTH_TOUCH_REQUIRED) ||
1442 !key_opts->no_require_user_presence;
1443 if (req_presence &&
1444 (sig_details->sk_flags & SSH_SK_USER_PRESENCE_REQD) == 0) {
1445 error("public key %s %s signature for %s%s from %.128s "
1446 "port %d rejected: user presence "
1447 "(authenticator touch) requirement not met ",
1448 sshkey_type(key), fp,
1449 authctxt->valid ? "" : "invalid user ",
1450 authctxt->user, ssh_remote_ipaddr(ssh),
1451 ssh_remote_port(ssh));
1452 ret = SSH_ERR_SIGNATURE_INVALID;
1453 }
1454 req_verify = (options.pubkey_auth_options &
1455 PUBKEYAUTH_VERIFY_REQUIRED) || key_opts->require_verify;
1456 if (req_verify &&
1457 (sig_details->sk_flags & SSH_SK_USER_VERIFICATION_REQD) == 0) {
1458 error("public key %s %s signature for %s%s from %.128s "
1459 "port %d rejected: user verification requirement "
1460 "not met ", sshkey_type(key), fp,
1461 authctxt->valid ? "" : "invalid user ",
1462 authctxt->user, ssh_remote_ipaddr(ssh),
1463 ssh_remote_port(ssh));
1464 ret = SSH_ERR_SIGNATURE_INVALID;
1465 }
1466 }
1467 auth2_record_key(authctxt, ret == 0, key);
1468
1469 if (key_blobtype == MM_USERKEY)
1470 auth_activate_options(ssh, key_opts);
1471 monitor_reset_key_state();
1472
1473 sshbuf_reset(m);
1474
1475 /* encode ret != 0 as positive integer, since we're sending u32 */
1476 encoded_ret = (ret != 0);
1477 if ((r = sshbuf_put_u32(m, encoded_ret)) != 0 ||
1478 (r = sshbuf_put_u8(m, sig_details != NULL)) != 0)
1479 fatal_fr(r, "assemble");
1480 if (sig_details != NULL) {
1481 if ((r = sshbuf_put_u32(m, sig_details->sk_counter)) != 0 ||
1482 (r = sshbuf_put_u8(m, sig_details->sk_flags)) != 0)
1483 fatal_fr(r, "assemble sk");
1484 }
1485 sshkey_sig_details_free(sig_details);
1486 mm_request_send(sock, MONITOR_ANS_KEYVERIFY, m);
1487
1488 free(sigalg);
1489 free(fp);
1490 sshkey_free(key);
1491
1492 return ret == 0;
1493 }
1494
1495 static void
mm_record_login(struct ssh * ssh,Session * s,struct passwd * pw)1496 mm_record_login(struct ssh *ssh, Session *s, struct passwd *pw)
1497 {
1498 socklen_t fromlen;
1499 struct sockaddr_storage from;
1500
1501 /*
1502 * Get IP address of client. If the connection is not a socket, let
1503 * the address be 0.0.0.0.
1504 */
1505 memset(&from, 0, sizeof(from));
1506 fromlen = sizeof(from);
1507 if (ssh_packet_connection_is_on_socket(ssh)) {
1508 if (getpeername(ssh_packet_get_connection_in(ssh),
1509 (struct sockaddr *)&from, &fromlen) == -1) {
1510 debug("getpeername: %.100s", strerror(errno));
1511 cleanup_exit(255);
1512 }
1513 }
1514 /* Record that there was a login on that tty from the remote host. */
1515 record_login(s->pid, s->tty, pw->pw_name, pw->pw_uid,
1516 session_get_remote_name_or_ip(ssh, utmp_len, options.use_dns),
1517 (struct sockaddr *)&from, fromlen);
1518 }
1519
1520 static void
mm_session_close(Session * s)1521 mm_session_close(Session *s)
1522 {
1523 debug3_f("session %d pid %ld", s->self, (long)s->pid);
1524 if (s->ttyfd != -1) {
1525 debug3_f("tty %s ptyfd %d", s->tty, s->ptyfd);
1526 session_pty_cleanup2(s);
1527 }
1528 session_unused(s->self);
1529 }
1530
1531 int
mm_answer_pty(struct ssh * ssh,int sock,struct sshbuf * m)1532 mm_answer_pty(struct ssh *ssh, int sock, struct sshbuf *m)
1533 {
1534 extern struct monitor *pmonitor;
1535 Session *s;
1536 int r, res, fd0;
1537
1538 debug3_f("entering");
1539
1540 sshbuf_reset(m);
1541 s = session_new();
1542 if (s == NULL)
1543 goto error;
1544 s->authctxt = authctxt;
1545 s->pw = authctxt->pw;
1546 s->pid = pmonitor->m_pid;
1547 res = pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty));
1548 if (res == 0)
1549 goto error;
1550 pty_setowner(authctxt->pw, s->tty);
1551
1552 if ((r = sshbuf_put_u32(m, 1)) != 0 ||
1553 (r = sshbuf_put_cstring(m, s->tty)) != 0)
1554 fatal_fr(r, "assemble");
1555
1556 /* We need to trick ttyslot */
1557 if (dup2(s->ttyfd, 0) == -1)
1558 fatal_f("dup2");
1559
1560 mm_record_login(ssh, s, authctxt->pw);
1561
1562 /* Now we can close the file descriptor again */
1563 close(0);
1564
1565 /* send messages generated by record_login */
1566 if ((r = sshbuf_put_stringb(m, loginmsg)) != 0)
1567 fatal_fr(r, "assemble loginmsg");
1568 sshbuf_reset(loginmsg);
1569
1570 mm_request_send(sock, MONITOR_ANS_PTY, m);
1571
1572 if (mm_send_fd(sock, s->ptyfd) == -1 ||
1573 mm_send_fd(sock, s->ttyfd) == -1)
1574 fatal_f("send fds failed");
1575
1576 /* make sure nothing uses fd 0 */
1577 if ((fd0 = open(_PATH_DEVNULL, O_RDONLY)) == -1)
1578 fatal_f("open(/dev/null): %s", strerror(errno));
1579 if (fd0 != 0)
1580 error_f("fd0 %d != 0", fd0);
1581
1582 /* slave side of pty is not needed */
1583 close(s->ttyfd);
1584 s->ttyfd = s->ptyfd;
1585 /* no need to dup() because nobody closes ptyfd */
1586 s->ptymaster = s->ptyfd;
1587
1588 debug3_f("tty %s ptyfd %d", s->tty, s->ttyfd);
1589
1590 return (0);
1591
1592 error:
1593 if (s != NULL)
1594 mm_session_close(s);
1595 if ((r = sshbuf_put_u32(m, 0)) != 0)
1596 fatal_fr(r, "assemble 0");
1597 mm_request_send(sock, MONITOR_ANS_PTY, m);
1598 return (0);
1599 }
1600
1601 int
mm_answer_pty_cleanup(struct ssh * ssh,int sock,struct sshbuf * m)1602 mm_answer_pty_cleanup(struct ssh *ssh, int sock, struct sshbuf *m)
1603 {
1604 Session *s;
1605 char *tty;
1606 int r;
1607
1608 debug3_f("entering");
1609
1610 if ((r = sshbuf_get_cstring(m, &tty, NULL)) != 0)
1611 fatal_fr(r, "parse tty");
1612 if ((s = session_by_tty(tty)) != NULL)
1613 mm_session_close(s);
1614 sshbuf_reset(m);
1615 free(tty);
1616 return (0);
1617 }
1618
1619 int
mm_answer_term(struct ssh * ssh,int sock,struct sshbuf * req)1620 mm_answer_term(struct ssh *ssh, int sock, struct sshbuf *req)
1621 {
1622 extern struct monitor *pmonitor;
1623 int res, status;
1624
1625 debug3_f("tearing down sessions");
1626
1627 /* The child is terminating */
1628 session_destroy_all(ssh, &mm_session_close);
1629
1630 #ifdef USE_PAM
1631 if (options.use_pam)
1632 sshpam_cleanup();
1633 #endif
1634
1635 while (waitpid(pmonitor->m_pid, &status, 0) == -1)
1636 if (errno != EINTR)
1637 exit(1);
1638
1639 res = WIFEXITED(status) ? WEXITSTATUS(status) : 1;
1640
1641 /* Terminate process */
1642 exit(res);
1643 }
1644
1645 #ifdef SSH_AUDIT_EVENTS
1646 /* Report that an audit event occurred */
1647 int
mm_answer_audit_event(struct ssh * ssh,int socket,struct sshbuf * m)1648 mm_answer_audit_event(struct ssh *ssh, int socket, struct sshbuf *m)
1649 {
1650 u_int n;
1651 ssh_audit_event_t event;
1652 int r;
1653
1654 debug3("%s entering", __func__);
1655
1656 if ((r = sshbuf_get_u32(m, &n)) != 0)
1657 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1658 event = (ssh_audit_event_t)n;
1659 switch (event) {
1660 case SSH_AUTH_FAIL_PUBKEY:
1661 case SSH_AUTH_FAIL_HOSTBASED:
1662 case SSH_AUTH_FAIL_GSSAPI:
1663 case SSH_LOGIN_EXCEED_MAXTRIES:
1664 case SSH_LOGIN_ROOT_DENIED:
1665 case SSH_CONNECTION_CLOSE:
1666 case SSH_INVALID_USER:
1667 audit_event(ssh, event);
1668 break;
1669 default:
1670 fatal("Audit event type %d not permitted", event);
1671 }
1672
1673 return (0);
1674 }
1675
1676 int
mm_answer_audit_command(struct ssh * ssh,int socket,struct sshbuf * m)1677 mm_answer_audit_command(struct ssh *ssh, int socket, struct sshbuf *m)
1678 {
1679 char *cmd;
1680 int r;
1681
1682 debug3("%s entering", __func__);
1683 if ((r = sshbuf_get_cstring(m, &cmd, NULL)) != 0)
1684 fatal("%s: buffer error: %s", __func__, ssh_err(r));
1685 /* sanity check command, if so how? */
1686 audit_run_command(cmd);
1687 free(cmd);
1688 return (0);
1689 }
1690 #endif /* SSH_AUDIT_EVENTS */
1691
1692 void
monitor_clear_keystate(struct ssh * ssh,struct monitor * pmonitor)1693 monitor_clear_keystate(struct ssh *ssh, struct monitor *pmonitor)
1694 {
1695 ssh_clear_newkeys(ssh, MODE_IN);
1696 ssh_clear_newkeys(ssh, MODE_OUT);
1697 sshbuf_free(child_state);
1698 child_state = NULL;
1699 }
1700
1701 void
monitor_apply_keystate(struct ssh * ssh,struct monitor * pmonitor)1702 monitor_apply_keystate(struct ssh *ssh, struct monitor *pmonitor)
1703 {
1704 struct kex *kex;
1705 int r;
1706
1707 debug3_f("packet_set_state");
1708 if ((r = ssh_packet_set_state(ssh, child_state)) != 0)
1709 fatal_fr(r, "packet_set_state");
1710 sshbuf_free(child_state);
1711 child_state = NULL;
1712 if ((kex = ssh->kex) == NULL)
1713 fatal_f("internal error: ssh->kex == NULL");
1714 if (session_id2_len != sshbuf_len(ssh->kex->session_id)) {
1715 fatal_f("incorrect session id length %zu (expected %u)",
1716 sshbuf_len(ssh->kex->session_id), session_id2_len);
1717 }
1718 if (memcmp(sshbuf_ptr(ssh->kex->session_id), session_id2,
1719 session_id2_len) != 0)
1720 fatal_f("session ID mismatch");
1721 /* XXX set callbacks */
1722 #ifdef WITH_OPENSSL
1723 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server;
1724 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server;
1725 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server;
1726 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server;
1727 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server;
1728 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server;
1729 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server;
1730 # ifdef OPENSSL_HAS_ECC
1731 kex->kex[KEX_ECDH_SHA2] = kex_gen_server;
1732 # endif
1733 #endif /* WITH_OPENSSL */
1734 kex->kex[KEX_C25519_SHA256] = kex_gen_server;
1735 kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server;
1736 kex->load_host_public_key=&get_hostkey_public_by_type;
1737 kex->load_host_private_key=&get_hostkey_private_by_type;
1738 kex->host_key_index=&get_hostkey_index;
1739 kex->sign = sshd_hostkey_sign;
1740 }
1741
1742 /* This function requires careful sanity checking */
1743
1744 void
mm_get_keystate(struct ssh * ssh,struct monitor * pmonitor)1745 mm_get_keystate(struct ssh *ssh, struct monitor *pmonitor)
1746 {
1747 debug3_f("Waiting for new keys");
1748
1749 if ((child_state = sshbuf_new()) == NULL)
1750 fatal_f("sshbuf_new failed");
1751 mm_request_receive_expect(pmonitor->m_sendfd, MONITOR_REQ_KEYEXPORT,
1752 child_state);
1753 debug3_f("GOT new keys");
1754 }
1755
1756
1757 /* XXX */
1758
1759 #define FD_CLOSEONEXEC(x) do { \
1760 if (fcntl(x, F_SETFD, FD_CLOEXEC) == -1) \
1761 fatal("fcntl(%d, F_SETFD)", x); \
1762 } while (0)
1763
1764 static void
monitor_openfds(struct monitor * mon,int do_logfds)1765 monitor_openfds(struct monitor *mon, int do_logfds)
1766 {
1767 int pair[2];
1768 #ifdef SO_ZEROIZE
1769 int on = 1;
1770 #endif
1771
1772 if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1)
1773 fatal_f("socketpair: %s", strerror(errno));
1774 #ifdef SO_ZEROIZE
1775 if (setsockopt(pair[0], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1)
1776 error("setsockopt SO_ZEROIZE(0): %.100s", strerror(errno));
1777 if (setsockopt(pair[1], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1)
1778 error("setsockopt SO_ZEROIZE(1): %.100s", strerror(errno));
1779 #endif
1780 FD_CLOSEONEXEC(pair[0]);
1781 FD_CLOSEONEXEC(pair[1]);
1782 mon->m_recvfd = pair[0];
1783 mon->m_sendfd = pair[1];
1784
1785 if (do_logfds) {
1786 if (pipe(pair) == -1)
1787 fatal_f("pipe: %s", strerror(errno));
1788 FD_CLOSEONEXEC(pair[0]);
1789 FD_CLOSEONEXEC(pair[1]);
1790 mon->m_log_recvfd = pair[0];
1791 mon->m_log_sendfd = pair[1];
1792 } else
1793 mon->m_log_recvfd = mon->m_log_sendfd = -1;
1794 }
1795
1796 #define MM_MEMSIZE 65536
1797
1798 struct monitor *
monitor_init(void)1799 monitor_init(void)
1800 {
1801 struct monitor *mon;
1802
1803 mon = xcalloc(1, sizeof(*mon));
1804 monitor_openfds(mon, 1);
1805
1806 return mon;
1807 }
1808
1809 void
monitor_reinit(struct monitor * mon)1810 monitor_reinit(struct monitor *mon)
1811 {
1812 monitor_openfds(mon, 0);
1813 }
1814
1815 #ifdef GSSAPI
1816 int
mm_answer_gss_setup_ctx(struct ssh * ssh,int sock,struct sshbuf * m)1817 mm_answer_gss_setup_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
1818 {
1819 gss_OID_desc goid;
1820 OM_uint32 major;
1821 size_t len;
1822 u_char *p;
1823 int r;
1824
1825 if (!options.gss_authentication)
1826 fatal_f("GSSAPI authentication not enabled");
1827
1828 if ((r = sshbuf_get_string(m, &p, &len)) != 0)
1829 fatal_fr(r, "parse");
1830 goid.elements = p;
1831 goid.length = len;
1832
1833 major = ssh_gssapi_server_ctx(&gsscontext, &goid);
1834
1835 free(goid.elements);
1836
1837 sshbuf_reset(m);
1838 if ((r = sshbuf_put_u32(m, major)) != 0)
1839 fatal_fr(r, "assemble");
1840
1841 mm_request_send(sock, MONITOR_ANS_GSSSETUP, m);
1842
1843 /* Now we have a context, enable the step */
1844 monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 1);
1845
1846 return (0);
1847 }
1848
1849 int
mm_answer_gss_accept_ctx(struct ssh * ssh,int sock,struct sshbuf * m)1850 mm_answer_gss_accept_ctx(struct ssh *ssh, int sock, struct sshbuf *m)
1851 {
1852 gss_buffer_desc in;
1853 gss_buffer_desc out = GSS_C_EMPTY_BUFFER;
1854 OM_uint32 major, minor;
1855 OM_uint32 flags = 0; /* GSI needs this */
1856 int r;
1857
1858 if (!options.gss_authentication)
1859 fatal_f("GSSAPI authentication not enabled");
1860
1861 if ((r = ssh_gssapi_get_buffer_desc(m, &in)) != 0)
1862 fatal_fr(r, "ssh_gssapi_get_buffer_desc");
1863 major = ssh_gssapi_accept_ctx(gsscontext, &in, &out, &flags);
1864 free(in.value);
1865
1866 sshbuf_reset(m);
1867 if ((r = sshbuf_put_u32(m, major)) != 0 ||
1868 (r = sshbuf_put_string(m, out.value, out.length)) != 0 ||
1869 (r = sshbuf_put_u32(m, flags)) != 0)
1870 fatal_fr(r, "assemble");
1871 mm_request_send(sock, MONITOR_ANS_GSSSTEP, m);
1872
1873 gss_release_buffer(&minor, &out);
1874
1875 if (major == GSS_S_COMPLETE) {
1876 monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 0);
1877 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1);
1878 monitor_permit(mon_dispatch, MONITOR_REQ_GSSCHECKMIC, 1);
1879 }
1880 return (0);
1881 }
1882
1883 int
mm_answer_gss_checkmic(struct ssh * ssh,int sock,struct sshbuf * m)1884 mm_answer_gss_checkmic(struct ssh *ssh, int sock, struct sshbuf *m)
1885 {
1886 gss_buffer_desc gssbuf, mic;
1887 OM_uint32 ret;
1888 int r;
1889
1890 if (!options.gss_authentication)
1891 fatal_f("GSSAPI authentication not enabled");
1892
1893 if ((r = ssh_gssapi_get_buffer_desc(m, &gssbuf)) != 0 ||
1894 (r = ssh_gssapi_get_buffer_desc(m, &mic)) != 0)
1895 fatal_fr(r, "ssh_gssapi_get_buffer_desc");
1896
1897 ret = ssh_gssapi_checkmic(gsscontext, &gssbuf, &mic);
1898
1899 free(gssbuf.value);
1900 free(mic.value);
1901
1902 sshbuf_reset(m);
1903 if ((r = sshbuf_put_u32(m, ret)) != 0)
1904 fatal_fr(r, "assemble");
1905
1906 mm_request_send(sock, MONITOR_ANS_GSSCHECKMIC, m);
1907
1908 if (!GSS_ERROR(ret))
1909 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1);
1910
1911 return (0);
1912 }
1913
1914 int
mm_answer_gss_userok(struct ssh * ssh,int sock,struct sshbuf * m)1915 mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m)
1916 {
1917 int r, authenticated;
1918 const char *displayname;
1919
1920 if (!options.gss_authentication)
1921 fatal_f("GSSAPI authentication not enabled");
1922
1923 authenticated = authctxt->valid && ssh_gssapi_userok(authctxt->user);
1924
1925 sshbuf_reset(m);
1926 if ((r = sshbuf_put_u32(m, authenticated)) != 0)
1927 fatal_fr(r, "assemble");
1928
1929 debug3_f("sending result %d", authenticated);
1930 mm_request_send(sock, MONITOR_ANS_GSSUSEROK, m);
1931
1932 auth_method = "gssapi-with-mic";
1933
1934 if ((displayname = ssh_gssapi_displayname()) != NULL)
1935 auth2_record_info(authctxt, "%s", displayname);
1936
1937 /* Monitor loop will terminate if authenticated */
1938 return (authenticated);
1939 }
1940 #endif /* GSSAPI */
1941
1942