1 /* $OpenBSD: monitor.c,v 1.236 2023/05/10 10:04:20 dtucker 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 <sys/types.h> 29 #include <sys/wait.h> 30 #include <sys/socket.h> 31 #include <sys/tree.h> 32 #include <sys/queue.h> 33 34 #ifdef WITH_OPENSSL 35 #include <openssl/dh.h> 36 #endif 37 38 #include <errno.h> 39 #include <fcntl.h> 40 #include <limits.h> 41 #include <paths.h> 42 #include <poll.h> 43 #include <pwd.h> 44 #include <signal.h> 45 #include <stdarg.h> 46 #include <stdint.h> 47 #include <stdio.h> 48 #include <stdlib.h> 49 #include <string.h> 50 #include <unistd.h> 51 52 #include "atomicio.h" 53 #include "xmalloc.h" 54 #include "ssh.h" 55 #include "sshkey.h" 56 #include "sshbuf.h" 57 #include "hostfile.h" 58 #include "auth.h" 59 #include "cipher.h" 60 #include "kex.h" 61 #include "dh.h" 62 #include "packet.h" 63 #include "auth-options.h" 64 #include "sshpty.h" 65 #include "channels.h" 66 #include "session.h" 67 #include "sshlogin.h" 68 #include "canohost.h" 69 #include "log.h" 70 #include "misc.h" 71 #include "servconf.h" 72 #include "monitor.h" 73 #ifdef GSSAPI 74 #include "ssh-gss.h" 75 #endif 76 #include "monitor_wrap.h" 77 #include "monitor_fdpass.h" 78 #include "compat.h" 79 #include "ssh2.h" 80 #include "authfd.h" 81 #include "match.h" 82 #include "ssherr.h" 83 #include "sk-api.h" 84 85 #ifdef GSSAPI 86 static Gssctxt *gsscontext = NULL; 87 #endif 88 89 /* Imports */ 90 extern ServerOptions options; 91 extern u_int utmp_len; 92 extern struct sshbuf *loginmsg; 93 extern struct sshauthopt *auth_opts; /* XXX move to permanent ssh->authctxt? */ 94 95 /* State exported from the child */ 96 static struct sshbuf *child_state; 97 98 /* Functions on the monitor that answer unprivileged requests */ 99 100 int mm_answer_moduli(struct ssh *, int, struct sshbuf *); 101 int mm_answer_sign(struct ssh *, int, struct sshbuf *); 102 int mm_answer_pwnamallow(struct ssh *, int, struct sshbuf *); 103 int mm_answer_auth2_read_banner(struct ssh *, int, struct sshbuf *); 104 int mm_answer_authserv(struct ssh *, int, struct sshbuf *); 105 int mm_answer_authpassword(struct ssh *, int, struct sshbuf *); 106 int mm_answer_bsdauthquery(struct ssh *, int, struct sshbuf *); 107 int mm_answer_bsdauthrespond(struct ssh *, int, struct sshbuf *); 108 int mm_answer_keyallowed(struct ssh *, int, struct sshbuf *); 109 int mm_answer_keyverify(struct ssh *, int, struct sshbuf *); 110 int mm_answer_pty(struct ssh *, int, struct sshbuf *); 111 int mm_answer_pty_cleanup(struct ssh *, int, struct sshbuf *); 112 int mm_answer_term(struct ssh *, int, struct sshbuf *); 113 int mm_answer_sesskey(struct ssh *, int, struct sshbuf *); 114 int mm_answer_sessid(struct ssh *, int, struct sshbuf *); 115 116 #ifdef GSSAPI 117 int mm_answer_gss_setup_ctx(struct ssh *, int, struct sshbuf *); 118 int mm_answer_gss_accept_ctx(struct ssh *, int, struct sshbuf *); 119 int mm_answer_gss_userok(struct ssh *, int, struct sshbuf *); 120 int mm_answer_gss_checkmic(struct ssh *, int, struct sshbuf *); 121 #endif 122 123 static Authctxt *authctxt; 124 125 /* local state for key verify */ 126 static u_char *key_blob = NULL; 127 static size_t key_bloblen = 0; 128 static u_int key_blobtype = MM_NOKEY; 129 static struct sshauthopt *key_opts = NULL; 130 static char *hostbased_cuser = NULL; 131 static char *hostbased_chost = NULL; 132 static char *auth_method = "unknown"; 133 static char *auth_submethod = NULL; 134 static u_int session_id2_len = 0; 135 static u_char *session_id2 = NULL; 136 static pid_t monitor_child_pid; 137 138 struct mon_table { 139 enum monitor_reqtype type; 140 int flags; 141 int (*f)(struct ssh *, int, struct sshbuf *); 142 }; 143 144 #define MON_ISAUTH 0x0004 /* Required for Authentication */ 145 #define MON_AUTHDECIDE 0x0008 /* Decides Authentication */ 146 #define MON_ONCE 0x0010 /* Disable after calling */ 147 #define MON_ALOG 0x0020 /* Log auth attempt without authenticating */ 148 149 #define MON_AUTH (MON_ISAUTH|MON_AUTHDECIDE) 150 151 #define MON_PERMIT 0x1000 /* Request is permitted */ 152 153 static int monitor_read(struct ssh *, struct monitor *, struct mon_table *, 154 struct mon_table **); 155 static int monitor_read_log(struct monitor *); 156 157 struct mon_table mon_dispatch_proto20[] = { 158 #ifdef WITH_OPENSSL 159 {MONITOR_REQ_MODULI, MON_ONCE, mm_answer_moduli}, 160 #endif 161 {MONITOR_REQ_SIGN, MON_ONCE, mm_answer_sign}, 162 {MONITOR_REQ_PWNAM, MON_ONCE, mm_answer_pwnamallow}, 163 {MONITOR_REQ_AUTHSERV, MON_ONCE, mm_answer_authserv}, 164 {MONITOR_REQ_AUTH2_READ_BANNER, MON_ONCE, mm_answer_auth2_read_banner}, 165 {MONITOR_REQ_AUTHPASSWORD, MON_AUTH, mm_answer_authpassword}, 166 {MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery}, 167 {MONITOR_REQ_BSDAUTHRESPOND, MON_AUTH, mm_answer_bsdauthrespond}, 168 {MONITOR_REQ_KEYALLOWED, MON_ISAUTH, mm_answer_keyallowed}, 169 {MONITOR_REQ_KEYVERIFY, MON_AUTH, mm_answer_keyverify}, 170 #ifdef GSSAPI 171 {MONITOR_REQ_GSSSETUP, MON_ISAUTH, mm_answer_gss_setup_ctx}, 172 {MONITOR_REQ_GSSSTEP, 0, mm_answer_gss_accept_ctx}, 173 {MONITOR_REQ_GSSUSEROK, MON_ONCE|MON_AUTHDECIDE, mm_answer_gss_userok}, 174 {MONITOR_REQ_GSSCHECKMIC, MON_ONCE, mm_answer_gss_checkmic}, 175 #endif 176 {0, 0, NULL} 177 }; 178 179 struct mon_table mon_dispatch_postauth20[] = { 180 #ifdef WITH_OPENSSL 181 {MONITOR_REQ_MODULI, 0, mm_answer_moduli}, 182 #endif 183 {MONITOR_REQ_SIGN, 0, mm_answer_sign}, 184 {MONITOR_REQ_PTY, 0, mm_answer_pty}, 185 {MONITOR_REQ_PTYCLEANUP, 0, mm_answer_pty_cleanup}, 186 {MONITOR_REQ_TERM, 0, mm_answer_term}, 187 {0, 0, NULL} 188 }; 189 190 struct mon_table *mon_dispatch; 191 192 /* Specifies if a certain message is allowed at the moment */ 193 static void 194 monitor_permit(struct mon_table *ent, enum monitor_reqtype type, int permit) 195 { 196 while (ent->f != NULL) { 197 if (ent->type == type) { 198 ent->flags &= ~MON_PERMIT; 199 ent->flags |= permit ? MON_PERMIT : 0; 200 return; 201 } 202 ent++; 203 } 204 } 205 206 static void 207 monitor_permit_authentications(int permit) 208 { 209 struct mon_table *ent = mon_dispatch; 210 211 while (ent->f != NULL) { 212 if (ent->flags & MON_AUTH) { 213 ent->flags &= ~MON_PERMIT; 214 ent->flags |= permit ? MON_PERMIT : 0; 215 } 216 ent++; 217 } 218 } 219 220 void 221 monitor_child_preauth(struct ssh *ssh, struct monitor *pmonitor) 222 { 223 struct mon_table *ent; 224 int authenticated = 0, partial = 0; 225 226 debug3("preauth child monitor started"); 227 228 if (pmonitor->m_recvfd >= 0) 229 close(pmonitor->m_recvfd); 230 if (pmonitor->m_log_sendfd >= 0) 231 close(pmonitor->m_log_sendfd); 232 pmonitor->m_log_sendfd = pmonitor->m_recvfd = -1; 233 234 authctxt = (Authctxt *)ssh->authctxt; 235 memset(authctxt, 0, sizeof(*authctxt)); 236 ssh->authctxt = authctxt; 237 238 mon_dispatch = mon_dispatch_proto20; 239 /* Permit requests for moduli and signatures */ 240 monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); 241 monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); 242 243 /* The first few requests do not require asynchronous access */ 244 while (!authenticated) { 245 partial = 0; 246 auth_method = "unknown"; 247 auth_submethod = NULL; 248 auth2_authctxt_reset_info(authctxt); 249 250 authenticated = (monitor_read(ssh, pmonitor, 251 mon_dispatch, &ent) == 1); 252 253 /* Special handling for multiple required authentications */ 254 if (options.num_auth_methods != 0) { 255 if (authenticated && 256 !auth2_update_methods_lists(authctxt, 257 auth_method, auth_submethod)) { 258 debug3_f("method %s: partial", auth_method); 259 authenticated = 0; 260 partial = 1; 261 } 262 } 263 264 if (authenticated) { 265 if (!(ent->flags & MON_AUTHDECIDE)) 266 fatal_f("unexpected authentication from %d", 267 ent->type); 268 if (authctxt->pw->pw_uid == 0 && 269 !auth_root_allowed(ssh, auth_method)) 270 authenticated = 0; 271 } 272 if (ent->flags & (MON_AUTHDECIDE|MON_ALOG)) { 273 auth_log(ssh, authenticated, partial, 274 auth_method, auth_submethod); 275 if (!partial && !authenticated) 276 authctxt->failures++; 277 if (authenticated || partial) { 278 auth2_update_session_info(authctxt, 279 auth_method, auth_submethod); 280 } 281 } 282 } 283 284 if (!authctxt->valid) 285 fatal_f("authenticated invalid user"); 286 if (strcmp(auth_method, "unknown") == 0) 287 fatal_f("authentication method name unknown"); 288 289 debug_f("user %s authenticated by privileged process", authctxt->user); 290 ssh->authctxt = NULL; 291 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 292 293 mm_get_keystate(ssh, pmonitor); 294 295 /* Drain any buffered messages from the child */ 296 while (pmonitor->m_log_recvfd != -1 && monitor_read_log(pmonitor) == 0) 297 ; 298 299 if (pmonitor->m_recvfd >= 0) 300 close(pmonitor->m_recvfd); 301 if (pmonitor->m_log_sendfd >= 0) 302 close(pmonitor->m_log_sendfd); 303 pmonitor->m_sendfd = pmonitor->m_log_recvfd = -1; 304 } 305 306 static void 307 monitor_set_child_handler(pid_t pid) 308 { 309 monitor_child_pid = pid; 310 } 311 312 static void 313 monitor_child_handler(int sig) 314 { 315 kill(monitor_child_pid, sig); 316 } 317 318 void 319 monitor_child_postauth(struct ssh *ssh, struct monitor *pmonitor) 320 { 321 close(pmonitor->m_recvfd); 322 pmonitor->m_recvfd = -1; 323 324 monitor_set_child_handler(pmonitor->m_pid); 325 ssh_signal(SIGHUP, &monitor_child_handler); 326 ssh_signal(SIGTERM, &monitor_child_handler); 327 ssh_signal(SIGINT, &monitor_child_handler); 328 329 mon_dispatch = mon_dispatch_postauth20; 330 331 /* Permit requests for moduli and signatures */ 332 monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); 333 monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); 334 monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1); 335 336 if (auth_opts->permit_pty_flag) { 337 monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1); 338 monitor_permit(mon_dispatch, MONITOR_REQ_PTYCLEANUP, 1); 339 } 340 341 for (;;) 342 monitor_read(ssh, pmonitor, mon_dispatch, NULL); 343 } 344 345 static int 346 monitor_read_log(struct monitor *pmonitor) 347 { 348 struct sshbuf *logmsg; 349 u_int len, level, forced; 350 char *msg; 351 u_char *p; 352 int r; 353 354 if ((logmsg = sshbuf_new()) == NULL) 355 fatal_f("sshbuf_new"); 356 357 /* Read length */ 358 if ((r = sshbuf_reserve(logmsg, 4, &p)) != 0) 359 fatal_fr(r, "reserve len"); 360 if (atomicio(read, pmonitor->m_log_recvfd, p, 4) != 4) { 361 if (errno == EPIPE) { 362 sshbuf_free(logmsg); 363 debug_f("child log fd closed"); 364 close(pmonitor->m_log_recvfd); 365 pmonitor->m_log_recvfd = -1; 366 return -1; 367 } 368 fatal_f("log fd read: %s", strerror(errno)); 369 } 370 if ((r = sshbuf_get_u32(logmsg, &len)) != 0) 371 fatal_fr(r, "parse len"); 372 if (len <= 4 || len > 8192) 373 fatal_f("invalid log message length %u", len); 374 375 /* Read severity, message */ 376 sshbuf_reset(logmsg); 377 if ((r = sshbuf_reserve(logmsg, len, &p)) != 0) 378 fatal_fr(r, "reserve msg"); 379 if (atomicio(read, pmonitor->m_log_recvfd, p, len) != len) 380 fatal_f("log fd read: %s", strerror(errno)); 381 if ((r = sshbuf_get_u32(logmsg, &level)) != 0 || 382 (r = sshbuf_get_u32(logmsg, &forced)) != 0 || 383 (r = sshbuf_get_cstring(logmsg, &msg, NULL)) != 0) 384 fatal_fr(r, "parse"); 385 386 /* Log it */ 387 if (log_level_name(level) == NULL) 388 fatal_f("invalid log level %u (corrupted message?)", level); 389 sshlogdirect(level, forced, "%s [preauth]", msg); 390 391 sshbuf_free(logmsg); 392 free(msg); 393 394 return 0; 395 } 396 397 static int 398 monitor_read(struct ssh *ssh, struct monitor *pmonitor, struct mon_table *ent, 399 struct mon_table **pent) 400 { 401 struct sshbuf *m; 402 int r, ret; 403 u_char type; 404 struct pollfd pfd[2]; 405 406 for (;;) { 407 memset(&pfd, 0, sizeof(pfd)); 408 pfd[0].fd = pmonitor->m_sendfd; 409 pfd[0].events = POLLIN; 410 pfd[1].fd = pmonitor->m_log_recvfd; 411 pfd[1].events = pfd[1].fd == -1 ? 0 : POLLIN; 412 if (poll(pfd, pfd[1].fd == -1 ? 1 : 2, -1) == -1) { 413 if (errno == EINTR || errno == EAGAIN) 414 continue; 415 fatal_f("poll: %s", strerror(errno)); 416 } 417 if (pfd[1].revents) { 418 /* 419 * Drain all log messages before processing next 420 * monitor request. 421 */ 422 monitor_read_log(pmonitor); 423 continue; 424 } 425 if (pfd[0].revents) 426 break; /* Continues below */ 427 } 428 429 if ((m = sshbuf_new()) == NULL) 430 fatal_f("sshbuf_new"); 431 432 mm_request_receive(pmonitor->m_sendfd, m); 433 if ((r = sshbuf_get_u8(m, &type)) != 0) 434 fatal_fr(r, "parse type"); 435 436 debug3_f("checking request %d", type); 437 438 while (ent->f != NULL) { 439 if (ent->type == type) 440 break; 441 ent++; 442 } 443 444 if (ent->f != NULL) { 445 if (!(ent->flags & MON_PERMIT)) 446 fatal_f("unpermitted request %d", type); 447 ret = (*ent->f)(ssh, pmonitor->m_sendfd, m); 448 sshbuf_free(m); 449 450 /* The child may use this request only once, disable it */ 451 if (ent->flags & MON_ONCE) { 452 debug2_f("%d used once, disabling now", type); 453 ent->flags &= ~MON_PERMIT; 454 } 455 456 if (pent != NULL) 457 *pent = ent; 458 459 return ret; 460 } 461 462 fatal_f("unsupported request: %d", type); 463 464 /* NOTREACHED */ 465 return (-1); 466 } 467 468 /* allowed key state */ 469 static int 470 monitor_allowed_key(const u_char *blob, u_int bloblen) 471 { 472 /* make sure key is allowed */ 473 if (key_blob == NULL || key_bloblen != bloblen || 474 timingsafe_bcmp(key_blob, blob, key_bloblen)) 475 return (0); 476 return (1); 477 } 478 479 static void 480 monitor_reset_key_state(void) 481 { 482 /* reset state */ 483 free(key_blob); 484 free(hostbased_cuser); 485 free(hostbased_chost); 486 sshauthopt_free(key_opts); 487 key_blob = NULL; 488 key_bloblen = 0; 489 key_blobtype = MM_NOKEY; 490 key_opts = NULL; 491 hostbased_cuser = NULL; 492 hostbased_chost = NULL; 493 } 494 495 #ifdef WITH_OPENSSL 496 int 497 mm_answer_moduli(struct ssh *ssh, int sock, struct sshbuf *m) 498 { 499 DH *dh; 500 const BIGNUM *dh_p, *dh_g; 501 int r; 502 u_int min, want, max; 503 504 if ((r = sshbuf_get_u32(m, &min)) != 0 || 505 (r = sshbuf_get_u32(m, &want)) != 0 || 506 (r = sshbuf_get_u32(m, &max)) != 0) 507 fatal_fr(r, "parse"); 508 509 debug3_f("got parameters: %d %d %d", min, want, max); 510 /* We need to check here, too, in case the child got corrupted */ 511 if (max < min || want < min || max < want) 512 fatal_f("bad parameters: %d %d %d", min, want, max); 513 514 sshbuf_reset(m); 515 516 dh = choose_dh(min, want, max); 517 if (dh == NULL) { 518 if ((r = sshbuf_put_u8(m, 0)) != 0) 519 fatal_fr(r, "assemble empty"); 520 return (0); 521 } else { 522 /* Send first bignum */ 523 DH_get0_pqg(dh, &dh_p, NULL, &dh_g); 524 if ((r = sshbuf_put_u8(m, 1)) != 0 || 525 (r = sshbuf_put_bignum2(m, dh_p)) != 0 || 526 (r = sshbuf_put_bignum2(m, dh_g)) != 0) 527 fatal_fr(r, "assemble"); 528 529 DH_free(dh); 530 } 531 mm_request_send(sock, MONITOR_ANS_MODULI, m); 532 return (0); 533 } 534 #endif 535 536 int 537 mm_answer_sign(struct ssh *ssh, int sock, struct sshbuf *m) 538 { 539 extern int auth_sock; /* XXX move to state struct? */ 540 struct sshkey *key; 541 struct sshbuf *sigbuf = NULL; 542 u_char *p = NULL, *signature = NULL; 543 char *alg = NULL; 544 size_t datlen, siglen, alglen; 545 int r, is_proof = 0; 546 u_int keyid, compat; 547 const char proof_req[] = "hostkeys-prove-00@openssh.com"; 548 549 debug3_f("entering"); 550 551 if ((r = sshbuf_get_u32(m, &keyid)) != 0 || 552 (r = sshbuf_get_string(m, &p, &datlen)) != 0 || 553 (r = sshbuf_get_cstring(m, &alg, &alglen)) != 0 || 554 (r = sshbuf_get_u32(m, &compat)) != 0) 555 fatal_fr(r, "parse"); 556 if (keyid > INT_MAX) 557 fatal_f("invalid key ID"); 558 559 /* 560 * Supported KEX types use SHA1 (20 bytes), SHA256 (32 bytes), 561 * SHA384 (48 bytes) and SHA512 (64 bytes). 562 * 563 * Otherwise, verify the signature request is for a hostkey 564 * proof. 565 * 566 * XXX perform similar check for KEX signature requests too? 567 * it's not trivial, since what is signed is the hash, rather 568 * than the full kex structure... 569 */ 570 if (datlen != 20 && datlen != 32 && datlen != 48 && datlen != 64) { 571 /* 572 * Construct expected hostkey proof and compare it to what 573 * the client sent us. 574 */ 575 if (session_id2_len == 0) /* hostkeys is never first */ 576 fatal_f("bad data length: %zu", datlen); 577 if ((key = get_hostkey_public_by_index(keyid, ssh)) == NULL) 578 fatal_f("no hostkey for index %d", keyid); 579 if ((sigbuf = sshbuf_new()) == NULL) 580 fatal_f("sshbuf_new"); 581 if ((r = sshbuf_put_cstring(sigbuf, proof_req)) != 0 || 582 (r = sshbuf_put_string(sigbuf, session_id2, 583 session_id2_len)) != 0 || 584 (r = sshkey_puts(key, sigbuf)) != 0) 585 fatal_fr(r, "assemble private key proof"); 586 if (datlen != sshbuf_len(sigbuf) || 587 memcmp(p, sshbuf_ptr(sigbuf), sshbuf_len(sigbuf)) != 0) 588 fatal_f("bad data length: %zu, hostkey proof len %zu", 589 datlen, sshbuf_len(sigbuf)); 590 sshbuf_free(sigbuf); 591 is_proof = 1; 592 } 593 594 /* save session id, it will be passed on the first call */ 595 if (session_id2_len == 0) { 596 session_id2_len = datlen; 597 session_id2 = xmalloc(session_id2_len); 598 memcpy(session_id2, p, session_id2_len); 599 } 600 601 if ((key = get_hostkey_by_index(keyid)) != NULL) { 602 if ((r = sshkey_sign(key, &signature, &siglen, p, datlen, alg, 603 options.sk_provider, NULL, compat)) != 0) 604 fatal_fr(r, "sign"); 605 } else if ((key = get_hostkey_public_by_index(keyid, ssh)) != NULL && 606 auth_sock > 0) { 607 if ((r = ssh_agent_sign(auth_sock, key, &signature, &siglen, 608 p, datlen, alg, compat)) != 0) 609 fatal_fr(r, "agent sign"); 610 } else 611 fatal_f("no hostkey from index %d", keyid); 612 613 debug3_f("%s %s signature len=%zu", alg, 614 is_proof ? "hostkey proof" : "KEX", siglen); 615 616 sshbuf_reset(m); 617 if ((r = sshbuf_put_string(m, signature, siglen)) != 0) 618 fatal_fr(r, "assemble"); 619 620 free(alg); 621 free(p); 622 free(signature); 623 624 mm_request_send(sock, MONITOR_ANS_SIGN, m); 625 626 /* Turn on permissions for getpwnam */ 627 monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1); 628 629 return (0); 630 } 631 632 #define PUTPW(b, id) \ 633 do { \ 634 if ((r = sshbuf_put_string(b, \ 635 &pwent->id, sizeof(pwent->id))) != 0) \ 636 fatal_fr(r, "assemble %s", #id); \ 637 } while (0) 638 639 /* Retrieves the password entry and also checks if the user is permitted */ 640 int 641 mm_answer_pwnamallow(struct ssh *ssh, int sock, struct sshbuf *m) 642 { 643 struct passwd *pwent; 644 int r, allowed = 0; 645 u_int i; 646 647 debug3_f("entering"); 648 649 if (authctxt->attempt++ != 0) 650 fatal_f("multiple attempts for getpwnam"); 651 652 if ((r = sshbuf_get_cstring(m, &authctxt->user, NULL)) != 0) 653 fatal_fr(r, "parse"); 654 655 pwent = getpwnamallow(ssh, authctxt->user); 656 657 setproctitle("%s [priv]", pwent ? authctxt->user : "unknown"); 658 659 sshbuf_reset(m); 660 661 if (pwent == NULL) { 662 if ((r = sshbuf_put_u8(m, 0)) != 0) 663 fatal_fr(r, "assemble fakepw"); 664 authctxt->pw = fakepw(); 665 goto out; 666 } 667 668 allowed = 1; 669 authctxt->pw = pwent; 670 authctxt->valid = 1; 671 672 /* XXX send fake class/dir/shell, etc. */ 673 if ((r = sshbuf_put_u8(m, 1)) != 0) 674 fatal_fr(r, "assemble ok"); 675 PUTPW(m, pw_uid); 676 PUTPW(m, pw_gid); 677 PUTPW(m, pw_change); 678 PUTPW(m, pw_expire); 679 if ((r = sshbuf_put_cstring(m, pwent->pw_name)) != 0 || 680 (r = sshbuf_put_cstring(m, "*")) != 0 || 681 (r = sshbuf_put_cstring(m, pwent->pw_gecos)) != 0 || 682 (r = sshbuf_put_cstring(m, pwent->pw_class)) != 0 || 683 (r = sshbuf_put_cstring(m, pwent->pw_dir)) != 0 || 684 (r = sshbuf_put_cstring(m, pwent->pw_shell)) != 0) 685 fatal_fr(r, "assemble pw"); 686 687 out: 688 ssh_packet_set_log_preamble(ssh, "%suser %s", 689 authctxt->valid ? "authenticating" : "invalid ", authctxt->user); 690 if ((r = sshbuf_put_string(m, &options, sizeof(options))) != 0) 691 fatal_fr(r, "assemble options"); 692 693 #define M_CP_STROPT(x) do { \ 694 if (options.x != NULL && \ 695 (r = sshbuf_put_cstring(m, options.x)) != 0) \ 696 fatal_fr(r, "assemble %s", #x); \ 697 } while (0) 698 #define M_CP_STRARRAYOPT(x, nx) do { \ 699 for (i = 0; i < options.nx; i++) { \ 700 if ((r = sshbuf_put_cstring(m, options.x[i])) != 0) \ 701 fatal_fr(r, "assemble %s", #x); \ 702 } \ 703 } while (0) 704 /* See comment in servconf.h */ 705 COPY_MATCH_STRING_OPTS(); 706 #undef M_CP_STROPT 707 #undef M_CP_STRARRAYOPT 708 709 /* Create valid auth method lists */ 710 if (auth2_setup_methods_lists(authctxt) != 0) { 711 /* 712 * The monitor will continue long enough to let the child 713 * run to its packet_disconnect(), but it must not allow any 714 * authentication to succeed. 715 */ 716 debug_f("no valid authentication method lists"); 717 } 718 719 debug3_f("sending MONITOR_ANS_PWNAM: %d", allowed); 720 mm_request_send(sock, MONITOR_ANS_PWNAM, m); 721 722 /* Allow service/style information on the auth context */ 723 monitor_permit(mon_dispatch, MONITOR_REQ_AUTHSERV, 1); 724 monitor_permit(mon_dispatch, MONITOR_REQ_AUTH2_READ_BANNER, 1); 725 726 return (0); 727 } 728 729 int mm_answer_auth2_read_banner(struct ssh *ssh, int sock, struct sshbuf *m) 730 { 731 char *banner; 732 int r; 733 734 sshbuf_reset(m); 735 banner = auth2_read_banner(); 736 if ((r = sshbuf_put_cstring(m, banner != NULL ? banner : "")) != 0) 737 fatal_fr(r, "assemble"); 738 mm_request_send(sock, MONITOR_ANS_AUTH2_READ_BANNER, m); 739 free(banner); 740 741 return (0); 742 } 743 744 int 745 mm_answer_authserv(struct ssh *ssh, int sock, struct sshbuf *m) 746 { 747 int r; 748 749 monitor_permit_authentications(1); 750 751 if ((r = sshbuf_get_cstring(m, &authctxt->service, NULL)) != 0 || 752 (r = sshbuf_get_cstring(m, &authctxt->style, NULL)) != 0) 753 fatal_fr(r, "parse"); 754 debug3_f("service=%s, style=%s", authctxt->service, authctxt->style); 755 756 if (strlen(authctxt->style) == 0) { 757 free(authctxt->style); 758 authctxt->style = NULL; 759 } 760 761 return (0); 762 } 763 764 int 765 mm_answer_authpassword(struct ssh *ssh, int sock, struct sshbuf *m) 766 { 767 static int call_count; 768 char *passwd; 769 int r, authenticated; 770 size_t plen; 771 772 if (!options.password_authentication) 773 fatal_f("password authentication not enabled"); 774 if ((r = sshbuf_get_cstring(m, &passwd, &plen)) != 0) 775 fatal_fr(r, "parse"); 776 /* Only authenticate if the context is valid */ 777 authenticated = options.password_authentication && 778 auth_password(ssh, passwd); 779 freezero(passwd, plen); 780 781 sshbuf_reset(m); 782 if ((r = sshbuf_put_u32(m, authenticated)) != 0) 783 fatal_fr(r, "assemble"); 784 785 debug3_f("sending result %d", authenticated); 786 mm_request_send(sock, MONITOR_ANS_AUTHPASSWORD, m); 787 788 call_count++; 789 if (plen == 0 && call_count == 1) 790 auth_method = "none"; 791 else 792 auth_method = "password"; 793 794 /* Causes monitor loop to terminate if authenticated */ 795 return (authenticated); 796 } 797 798 int 799 mm_answer_bsdauthquery(struct ssh *ssh, int sock, struct sshbuf *m) 800 { 801 char *name, *infotxt; 802 u_int numprompts, *echo_on, success; 803 char **prompts; 804 int r; 805 806 if (!options.kbd_interactive_authentication) 807 fatal_f("kbd-int authentication not enabled"); 808 success = bsdauth_query(authctxt, &name, &infotxt, &numprompts, 809 &prompts, &echo_on) < 0 ? 0 : 1; 810 811 sshbuf_reset(m); 812 if ((r = sshbuf_put_u32(m, success)) != 0) 813 fatal_fr(r, "assemble"); 814 if (success) { 815 if ((r = sshbuf_put_cstring(m, prompts[0])) != 0) 816 fatal_fr(r, "assemble prompt"); 817 } 818 819 debug3_f("sending challenge success: %u", success); 820 mm_request_send(sock, MONITOR_ANS_BSDAUTHQUERY, m); 821 822 if (success) { 823 free(name); 824 free(infotxt); 825 free(prompts); 826 free(echo_on); 827 } 828 829 return (0); 830 } 831 832 int 833 mm_answer_bsdauthrespond(struct ssh *ssh, int sock, struct sshbuf *m) 834 { 835 char *response; 836 int r, authok; 837 838 if (!options.kbd_interactive_authentication) 839 fatal_f("kbd-int authentication not enabled"); 840 if (authctxt->as == NULL) 841 fatal_f("no bsd auth session"); 842 843 if ((r = sshbuf_get_cstring(m, &response, NULL)) != 0) 844 fatal_fr(r, "parse"); 845 authok = options.kbd_interactive_authentication && 846 auth_userresponse(authctxt->as, response, 0); 847 authctxt->as = NULL; 848 debug3_f("<%s> = <%d>", response, authok); 849 free(response); 850 851 sshbuf_reset(m); 852 if ((r = sshbuf_put_u32(m, authok)) != 0) 853 fatal_fr(r, "assemble"); 854 855 debug3_f("sending authenticated: %d", authok); 856 mm_request_send(sock, MONITOR_ANS_BSDAUTHRESPOND, m); 857 858 auth_method = "keyboard-interactive"; 859 auth_submethod = "bsdauth"; 860 861 return (authok != 0); 862 } 863 864 /* 865 * Check that the key type appears in the supplied pattern list, ignoring 866 * mismatches in the signature algorithm. (Signature algorithm checks are 867 * performed in the unprivileged authentication code). 868 * Returns 1 on success, 0 otherwise. 869 */ 870 static int 871 key_base_type_match(const char *method, const struct sshkey *key, 872 const char *list) 873 { 874 char *s, *l, *ol = xstrdup(list); 875 int found = 0; 876 877 l = ol; 878 for ((s = strsep(&l, ",")); s && *s != '\0'; (s = strsep(&l, ","))) { 879 if (sshkey_type_from_name(s) == key->type) { 880 found = 1; 881 break; 882 } 883 } 884 if (!found) { 885 error("%s key type %s is not in permitted list %s", method, 886 sshkey_ssh_name(key), list); 887 } 888 889 free(ol); 890 return found; 891 } 892 893 int 894 mm_answer_keyallowed(struct ssh *ssh, int sock, struct sshbuf *m) 895 { 896 struct sshkey *key = NULL; 897 char *cuser, *chost; 898 u_int pubkey_auth_attempt; 899 u_int type = 0; 900 int r, allowed = 0; 901 struct sshauthopt *opts = NULL; 902 903 debug3_f("entering"); 904 if ((r = sshbuf_get_u32(m, &type)) != 0 || 905 (r = sshbuf_get_cstring(m, &cuser, NULL)) != 0 || 906 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 || 907 (r = sshkey_froms(m, &key)) != 0 || 908 (r = sshbuf_get_u32(m, &pubkey_auth_attempt)) != 0) 909 fatal_fr(r, "parse"); 910 911 if (key != NULL && authctxt->valid) { 912 switch (type) { 913 case MM_USERKEY: 914 auth_method = "publickey"; 915 if (!options.pubkey_authentication) 916 break; 917 if (auth2_key_already_used(authctxt, key)) 918 break; 919 if (!key_base_type_match(auth_method, key, 920 options.pubkey_accepted_algos)) 921 break; 922 allowed = user_key_allowed(ssh, authctxt->pw, key, 923 pubkey_auth_attempt, &opts); 924 break; 925 case MM_HOSTKEY: 926 auth_method = "hostbased"; 927 if (!options.hostbased_authentication) 928 break; 929 if (auth2_key_already_used(authctxt, key)) 930 break; 931 if (!key_base_type_match(auth_method, key, 932 options.hostbased_accepted_algos)) 933 break; 934 allowed = hostbased_key_allowed(ssh, authctxt->pw, 935 cuser, chost, key); 936 auth2_record_info(authctxt, 937 "client user \"%.100s\", client host \"%.100s\"", 938 cuser, chost); 939 break; 940 default: 941 fatal_f("unknown key type %u", type); 942 break; 943 } 944 } 945 946 debug3_f("%s authentication%s: %s key is %s", auth_method, 947 pubkey_auth_attempt ? "" : " test", 948 (key == NULL || !authctxt->valid) ? "invalid" : sshkey_type(key), 949 allowed ? "allowed" : "not allowed"); 950 951 auth2_record_key(authctxt, 0, key); 952 953 /* clear temporarily storage (used by verify) */ 954 monitor_reset_key_state(); 955 956 if (allowed) { 957 /* Save temporarily for comparison in verify */ 958 if ((r = sshkey_to_blob(key, &key_blob, &key_bloblen)) != 0) 959 fatal_fr(r, "sshkey_to_blob"); 960 key_blobtype = type; 961 key_opts = opts; 962 hostbased_cuser = cuser; 963 hostbased_chost = chost; 964 } else { 965 /* Log failed attempt */ 966 auth_log(ssh, 0, 0, auth_method, NULL); 967 free(cuser); 968 free(chost); 969 } 970 sshkey_free(key); 971 972 sshbuf_reset(m); 973 if ((r = sshbuf_put_u32(m, allowed)) != 0) 974 fatal_fr(r, "assemble"); 975 if (opts != NULL && (r = sshauthopt_serialise(opts, m, 1)) != 0) 976 fatal_fr(r, "sshauthopt_serialise"); 977 mm_request_send(sock, MONITOR_ANS_KEYALLOWED, m); 978 979 if (!allowed) 980 sshauthopt_free(opts); 981 982 return (0); 983 } 984 985 static int 986 monitor_valid_userblob(struct ssh *ssh, const u_char *data, u_int datalen) 987 { 988 struct sshbuf *b; 989 struct sshkey *hostkey = NULL; 990 const u_char *p; 991 char *userstyle, *cp; 992 size_t len; 993 u_char type; 994 int hostbound = 0, r, fail = 0; 995 996 if ((b = sshbuf_from(data, datalen)) == NULL) 997 fatal_f("sshbuf_from"); 998 999 if (ssh->compat & SSH_OLD_SESSIONID) { 1000 p = sshbuf_ptr(b); 1001 len = sshbuf_len(b); 1002 if ((session_id2 == NULL) || 1003 (len < session_id2_len) || 1004 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) 1005 fail++; 1006 if ((r = sshbuf_consume(b, session_id2_len)) != 0) 1007 fatal_fr(r, "consume"); 1008 } else { 1009 if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0) 1010 fatal_fr(r, "parse sessionid"); 1011 if ((session_id2 == NULL) || 1012 (len != session_id2_len) || 1013 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) 1014 fail++; 1015 } 1016 if ((r = sshbuf_get_u8(b, &type)) != 0) 1017 fatal_fr(r, "parse type"); 1018 if (type != SSH2_MSG_USERAUTH_REQUEST) 1019 fail++; 1020 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1021 fatal_fr(r, "parse userstyle"); 1022 xasprintf(&userstyle, "%s%s%s", authctxt->user, 1023 authctxt->style ? ":" : "", 1024 authctxt->style ? authctxt->style : ""); 1025 if (strcmp(userstyle, cp) != 0) { 1026 logit("wrong user name passed to monitor: " 1027 "expected %s != %.100s", userstyle, cp); 1028 fail++; 1029 } 1030 free(userstyle); 1031 free(cp); 1032 if ((r = sshbuf_skip_string(b)) != 0 || /* service */ 1033 (r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1034 fatal_fr(r, "parse method"); 1035 if (strcmp("publickey", cp) != 0) { 1036 if (strcmp("publickey-hostbound-v00@openssh.com", cp) == 0) 1037 hostbound = 1; 1038 else 1039 fail++; 1040 } 1041 free(cp); 1042 if ((r = sshbuf_get_u8(b, &type)) != 0) 1043 fatal_fr(r, "parse pktype"); 1044 if (type == 0) 1045 fail++; 1046 if ((r = sshbuf_skip_string(b)) != 0 || /* pkalg */ 1047 (r = sshbuf_skip_string(b)) != 0 || /* pkblob */ 1048 (hostbound && (r = sshkey_froms(b, &hostkey)) != 0)) 1049 fatal_fr(r, "parse pk"); 1050 if (sshbuf_len(b) != 0) 1051 fail++; 1052 sshbuf_free(b); 1053 if (hostkey != NULL) { 1054 /* 1055 * Ensure this is actually one of our hostkeys; unfortunately 1056 * can't check ssh->kex->initial_hostkey directly at this point 1057 * as packet state has not yet been exported to monitor. 1058 */ 1059 if (get_hostkey_index(hostkey, 1, ssh) == -1) 1060 fatal_f("hostbound hostkey does not match"); 1061 sshkey_free(hostkey); 1062 } 1063 return (fail == 0); 1064 } 1065 1066 static int 1067 monitor_valid_hostbasedblob(const u_char *data, u_int datalen, 1068 const char *cuser, const char *chost) 1069 { 1070 struct sshbuf *b; 1071 const u_char *p; 1072 char *cp, *userstyle; 1073 size_t len; 1074 int r, fail = 0; 1075 u_char type; 1076 1077 if ((b = sshbuf_from(data, datalen)) == NULL) 1078 fatal_f("sshbuf_new"); 1079 if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0) 1080 fatal_fr(r, "parse sessionid"); 1081 1082 if ((session_id2 == NULL) || 1083 (len != session_id2_len) || 1084 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) 1085 fail++; 1086 1087 if ((r = sshbuf_get_u8(b, &type)) != 0) 1088 fatal_fr(r, "parse type"); 1089 if (type != SSH2_MSG_USERAUTH_REQUEST) 1090 fail++; 1091 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1092 fatal_fr(r, "parse userstyle"); 1093 xasprintf(&userstyle, "%s%s%s", authctxt->user, 1094 authctxt->style ? ":" : "", 1095 authctxt->style ? authctxt->style : ""); 1096 if (strcmp(userstyle, cp) != 0) { 1097 logit("wrong user name passed to monitor: " 1098 "expected %s != %.100s", userstyle, cp); 1099 fail++; 1100 } 1101 free(userstyle); 1102 free(cp); 1103 if ((r = sshbuf_skip_string(b)) != 0 || /* service */ 1104 (r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1105 fatal_fr(r, "parse method"); 1106 if (strcmp(cp, "hostbased") != 0) 1107 fail++; 1108 free(cp); 1109 if ((r = sshbuf_skip_string(b)) != 0 || /* pkalg */ 1110 (r = sshbuf_skip_string(b)) != 0) /* pkblob */ 1111 fatal_fr(r, "parse pk"); 1112 1113 /* verify client host, strip trailing dot if necessary */ 1114 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1115 fatal_fr(r, "parse host"); 1116 if (((len = strlen(cp)) > 0) && cp[len - 1] == '.') 1117 cp[len - 1] = '\0'; 1118 if (strcmp(cp, chost) != 0) 1119 fail++; 1120 free(cp); 1121 1122 /* verify client user */ 1123 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1124 fatal_fr(r, "parse ruser"); 1125 if (strcmp(cp, cuser) != 0) 1126 fail++; 1127 free(cp); 1128 1129 if (sshbuf_len(b) != 0) 1130 fail++; 1131 sshbuf_free(b); 1132 return (fail == 0); 1133 } 1134 1135 int 1136 mm_answer_keyverify(struct ssh *ssh, int sock, struct sshbuf *m) 1137 { 1138 struct sshkey *key; 1139 const u_char *signature, *data, *blob; 1140 char *sigalg = NULL, *fp = NULL; 1141 size_t signaturelen, datalen, bloblen; 1142 int r, ret, req_presence = 0, req_verify = 0, valid_data = 0; 1143 int encoded_ret; 1144 struct sshkey_sig_details *sig_details = NULL; 1145 1146 if ((r = sshbuf_get_string_direct(m, &blob, &bloblen)) != 0 || 1147 (r = sshbuf_get_string_direct(m, &signature, &signaturelen)) != 0 || 1148 (r = sshbuf_get_string_direct(m, &data, &datalen)) != 0 || 1149 (r = sshbuf_get_cstring(m, &sigalg, NULL)) != 0) 1150 fatal_fr(r, "parse"); 1151 1152 if (hostbased_cuser == NULL || hostbased_chost == NULL || 1153 !monitor_allowed_key(blob, bloblen)) 1154 fatal_f("bad key, not previously allowed"); 1155 1156 /* Empty signature algorithm means NULL. */ 1157 if (*sigalg == '\0') { 1158 free(sigalg); 1159 sigalg = NULL; 1160 } 1161 1162 /* XXX use sshkey_froms here; need to change key_blob, etc. */ 1163 if ((r = sshkey_from_blob(blob, bloblen, &key)) != 0) 1164 fatal_fr(r, "parse key"); 1165 1166 switch (key_blobtype) { 1167 case MM_USERKEY: 1168 valid_data = monitor_valid_userblob(ssh, data, datalen); 1169 auth_method = "publickey"; 1170 break; 1171 case MM_HOSTKEY: 1172 valid_data = monitor_valid_hostbasedblob(data, datalen, 1173 hostbased_cuser, hostbased_chost); 1174 auth_method = "hostbased"; 1175 break; 1176 default: 1177 valid_data = 0; 1178 break; 1179 } 1180 if (!valid_data) 1181 fatal_f("bad %s signature data blob", 1182 key_blobtype == MM_USERKEY ? "userkey" : 1183 (key_blobtype == MM_HOSTKEY ? "hostkey" : "unknown")); 1184 1185 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, 1186 SSH_FP_DEFAULT)) == NULL) 1187 fatal_f("sshkey_fingerprint failed"); 1188 1189 ret = sshkey_verify(key, signature, signaturelen, data, datalen, 1190 sigalg, ssh->compat, &sig_details); 1191 debug3_f("%s %s signature using %s %s%s%s", auth_method, 1192 sshkey_type(key), sigalg == NULL ? "default" : sigalg, 1193 (ret == 0) ? "verified" : "unverified", 1194 (ret != 0) ? ": " : "", (ret != 0) ? ssh_err(ret) : ""); 1195 1196 if (ret == 0 && key_blobtype == MM_USERKEY && sig_details != NULL) { 1197 req_presence = (options.pubkey_auth_options & 1198 PUBKEYAUTH_TOUCH_REQUIRED) || 1199 !key_opts->no_require_user_presence; 1200 if (req_presence && 1201 (sig_details->sk_flags & SSH_SK_USER_PRESENCE_REQD) == 0) { 1202 error("public key %s %s signature for %s%s from %.128s " 1203 "port %d rejected: user presence " 1204 "(authenticator touch) requirement not met ", 1205 sshkey_type(key), fp, 1206 authctxt->valid ? "" : "invalid user ", 1207 authctxt->user, ssh_remote_ipaddr(ssh), 1208 ssh_remote_port(ssh)); 1209 ret = SSH_ERR_SIGNATURE_INVALID; 1210 } 1211 req_verify = (options.pubkey_auth_options & 1212 PUBKEYAUTH_VERIFY_REQUIRED) || key_opts->require_verify; 1213 if (req_verify && 1214 (sig_details->sk_flags & SSH_SK_USER_VERIFICATION_REQD) == 0) { 1215 error("public key %s %s signature for %s%s from %.128s " 1216 "port %d rejected: user verification requirement " 1217 "not met ", sshkey_type(key), fp, 1218 authctxt->valid ? "" : "invalid user ", 1219 authctxt->user, ssh_remote_ipaddr(ssh), 1220 ssh_remote_port(ssh)); 1221 ret = SSH_ERR_SIGNATURE_INVALID; 1222 } 1223 } 1224 auth2_record_key(authctxt, ret == 0, key); 1225 1226 if (key_blobtype == MM_USERKEY) 1227 auth_activate_options(ssh, key_opts); 1228 monitor_reset_key_state(); 1229 1230 sshbuf_reset(m); 1231 1232 /* encode ret != 0 as positive integer, since we're sending u32 */ 1233 encoded_ret = (ret != 0); 1234 if ((r = sshbuf_put_u32(m, encoded_ret)) != 0 || 1235 (r = sshbuf_put_u8(m, sig_details != NULL)) != 0) 1236 fatal_fr(r, "assemble"); 1237 if (sig_details != NULL) { 1238 if ((r = sshbuf_put_u32(m, sig_details->sk_counter)) != 0 || 1239 (r = sshbuf_put_u8(m, sig_details->sk_flags)) != 0) 1240 fatal_fr(r, "assemble sk"); 1241 } 1242 sshkey_sig_details_free(sig_details); 1243 mm_request_send(sock, MONITOR_ANS_KEYVERIFY, m); 1244 1245 free(sigalg); 1246 free(fp); 1247 sshkey_free(key); 1248 1249 return ret == 0; 1250 } 1251 1252 static void 1253 mm_record_login(struct ssh *ssh, Session *s, struct passwd *pw) 1254 { 1255 socklen_t fromlen; 1256 struct sockaddr_storage from; 1257 1258 /* 1259 * Get IP address of client. If the connection is not a socket, let 1260 * the address be 0.0.0.0. 1261 */ 1262 memset(&from, 0, sizeof(from)); 1263 fromlen = sizeof(from); 1264 if (ssh_packet_connection_is_on_socket(ssh)) { 1265 if (getpeername(ssh_packet_get_connection_in(ssh), 1266 (struct sockaddr *)&from, &fromlen) == -1) { 1267 debug("getpeername: %.100s", strerror(errno)); 1268 cleanup_exit(255); 1269 } 1270 } 1271 /* Record that there was a login on that tty from the remote host. */ 1272 record_login(s->pid, s->tty, pw->pw_name, pw->pw_uid, 1273 session_get_remote_name_or_ip(ssh, utmp_len, options.use_dns), 1274 (struct sockaddr *)&from, fromlen); 1275 } 1276 1277 static void 1278 mm_session_close(Session *s) 1279 { 1280 debug3_f("session %d pid %ld", s->self, (long)s->pid); 1281 if (s->ttyfd != -1) { 1282 debug3_f("tty %s ptyfd %d", s->tty, s->ptyfd); 1283 session_pty_cleanup2(s); 1284 } 1285 session_unused(s->self); 1286 } 1287 1288 int 1289 mm_answer_pty(struct ssh *ssh, int sock, struct sshbuf *m) 1290 { 1291 extern struct monitor *pmonitor; 1292 Session *s; 1293 int r, res, fd0; 1294 1295 debug3_f("entering"); 1296 1297 sshbuf_reset(m); 1298 s = session_new(); 1299 if (s == NULL) 1300 goto error; 1301 s->authctxt = authctxt; 1302 s->pw = authctxt->pw; 1303 s->pid = pmonitor->m_pid; 1304 res = pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty)); 1305 if (res == 0) 1306 goto error; 1307 pty_setowner(authctxt->pw, s->tty); 1308 1309 if ((r = sshbuf_put_u32(m, 1)) != 0 || 1310 (r = sshbuf_put_cstring(m, s->tty)) != 0) 1311 fatal_fr(r, "assemble"); 1312 1313 /* We need to trick ttyslot */ 1314 if (dup2(s->ttyfd, 0) == -1) 1315 fatal_f("dup2"); 1316 1317 mm_record_login(ssh, s, authctxt->pw); 1318 1319 /* Now we can close the file descriptor again */ 1320 close(0); 1321 1322 /* send messages generated by record_login */ 1323 if ((r = sshbuf_put_stringb(m, loginmsg)) != 0) 1324 fatal_fr(r, "assemble loginmsg"); 1325 sshbuf_reset(loginmsg); 1326 1327 mm_request_send(sock, MONITOR_ANS_PTY, m); 1328 1329 if (mm_send_fd(sock, s->ptyfd) == -1 || 1330 mm_send_fd(sock, s->ttyfd) == -1) 1331 fatal_f("send fds failed"); 1332 1333 /* make sure nothing uses fd 0 */ 1334 if ((fd0 = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1335 fatal_f("open(/dev/null): %s", strerror(errno)); 1336 if (fd0 != 0) 1337 error_f("fd0 %d != 0", fd0); 1338 1339 /* slave side of pty is not needed */ 1340 close(s->ttyfd); 1341 s->ttyfd = s->ptyfd; 1342 /* no need to dup() because nobody closes ptyfd */ 1343 s->ptymaster = s->ptyfd; 1344 1345 debug3_f("tty %s ptyfd %d", s->tty, s->ttyfd); 1346 1347 return (0); 1348 1349 error: 1350 if (s != NULL) 1351 mm_session_close(s); 1352 if ((r = sshbuf_put_u32(m, 0)) != 0) 1353 fatal_fr(r, "assemble 0"); 1354 mm_request_send(sock, MONITOR_ANS_PTY, m); 1355 return (0); 1356 } 1357 1358 int 1359 mm_answer_pty_cleanup(struct ssh *ssh, int sock, struct sshbuf *m) 1360 { 1361 Session *s; 1362 char *tty; 1363 int r; 1364 1365 debug3_f("entering"); 1366 1367 if ((r = sshbuf_get_cstring(m, &tty, NULL)) != 0) 1368 fatal_fr(r, "parse tty"); 1369 if ((s = session_by_tty(tty)) != NULL) 1370 mm_session_close(s); 1371 sshbuf_reset(m); 1372 free(tty); 1373 return (0); 1374 } 1375 1376 int 1377 mm_answer_term(struct ssh *ssh, int sock, struct sshbuf *req) 1378 { 1379 extern struct monitor *pmonitor; 1380 int res, status; 1381 1382 debug3_f("tearing down sessions"); 1383 1384 /* The child is terminating */ 1385 session_destroy_all(ssh, &mm_session_close); 1386 1387 while (waitpid(pmonitor->m_pid, &status, 0) == -1) 1388 if (errno != EINTR) 1389 exit(1); 1390 1391 res = WIFEXITED(status) ? WEXITSTATUS(status) : 1; 1392 1393 /* Terminate process */ 1394 exit(res); 1395 } 1396 1397 void 1398 monitor_clear_keystate(struct ssh *ssh, struct monitor *pmonitor) 1399 { 1400 ssh_clear_newkeys(ssh, MODE_IN); 1401 ssh_clear_newkeys(ssh, MODE_OUT); 1402 sshbuf_free(child_state); 1403 child_state = NULL; 1404 } 1405 1406 void 1407 monitor_apply_keystate(struct ssh *ssh, struct monitor *pmonitor) 1408 { 1409 struct kex *kex; 1410 int r; 1411 1412 debug3_f("packet_set_state"); 1413 if ((r = ssh_packet_set_state(ssh, child_state)) != 0) 1414 fatal_fr(r, "packet_set_state"); 1415 sshbuf_free(child_state); 1416 child_state = NULL; 1417 if ((kex = ssh->kex) == NULL) 1418 fatal_f("internal error: ssh->kex == NULL"); 1419 if (session_id2_len != sshbuf_len(ssh->kex->session_id)) { 1420 fatal_f("incorrect session id length %zu (expected %u)", 1421 sshbuf_len(ssh->kex->session_id), session_id2_len); 1422 } 1423 if (memcmp(sshbuf_ptr(ssh->kex->session_id), session_id2, 1424 session_id2_len) != 0) 1425 fatal_f("session ID mismatch"); 1426 /* XXX set callbacks */ 1427 #ifdef WITH_OPENSSL 1428 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server; 1429 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server; 1430 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server; 1431 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server; 1432 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server; 1433 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 1434 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 1435 kex->kex[KEX_ECDH_SHA2] = kex_gen_server; 1436 #endif 1437 kex->kex[KEX_C25519_SHA256] = kex_gen_server; 1438 kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server; 1439 kex->load_host_public_key=&get_hostkey_public_by_type; 1440 kex->load_host_private_key=&get_hostkey_private_by_type; 1441 kex->host_key_index=&get_hostkey_index; 1442 kex->sign = sshd_hostkey_sign; 1443 } 1444 1445 /* This function requires careful sanity checking */ 1446 1447 void 1448 mm_get_keystate(struct ssh *ssh, struct monitor *pmonitor) 1449 { 1450 debug3_f("Waiting for new keys"); 1451 1452 if ((child_state = sshbuf_new()) == NULL) 1453 fatal_f("sshbuf_new failed"); 1454 mm_request_receive_expect(pmonitor->m_sendfd, MONITOR_REQ_KEYEXPORT, 1455 child_state); 1456 debug3_f("GOT new keys"); 1457 } 1458 1459 1460 /* XXX */ 1461 1462 #define FD_CLOSEONEXEC(x) do { \ 1463 if (fcntl(x, F_SETFD, FD_CLOEXEC) == -1) \ 1464 fatal("fcntl(%d, F_SETFD)", x); \ 1465 } while (0) 1466 1467 static void 1468 monitor_openfds(struct monitor *mon, int do_logfds) 1469 { 1470 int pair[2]; 1471 #ifdef SO_ZEROIZE 1472 int on = 1; 1473 #endif 1474 1475 if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) 1476 fatal_f("socketpair: %s", strerror(errno)); 1477 #ifdef SO_ZEROIZE 1478 if (setsockopt(pair[0], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1) 1479 error("setsockopt SO_ZEROIZE(0): %.100s", strerror(errno)); 1480 if (setsockopt(pair[1], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1) 1481 error("setsockopt SO_ZEROIZE(1): %.100s", strerror(errno)); 1482 #endif 1483 FD_CLOSEONEXEC(pair[0]); 1484 FD_CLOSEONEXEC(pair[1]); 1485 mon->m_recvfd = pair[0]; 1486 mon->m_sendfd = pair[1]; 1487 1488 if (do_logfds) { 1489 if (pipe(pair) == -1) 1490 fatal_f("pipe: %s", strerror(errno)); 1491 FD_CLOSEONEXEC(pair[0]); 1492 FD_CLOSEONEXEC(pair[1]); 1493 mon->m_log_recvfd = pair[0]; 1494 mon->m_log_sendfd = pair[1]; 1495 } else 1496 mon->m_log_recvfd = mon->m_log_sendfd = -1; 1497 } 1498 1499 #define MM_MEMSIZE 65536 1500 1501 struct monitor * 1502 monitor_init(void) 1503 { 1504 struct monitor *mon; 1505 1506 mon = xcalloc(1, sizeof(*mon)); 1507 monitor_openfds(mon, 1); 1508 1509 return mon; 1510 } 1511 1512 void 1513 monitor_reinit(struct monitor *mon) 1514 { 1515 monitor_openfds(mon, 0); 1516 } 1517 1518 #ifdef GSSAPI 1519 int 1520 mm_answer_gss_setup_ctx(struct ssh *ssh, int sock, struct sshbuf *m) 1521 { 1522 gss_OID_desc goid; 1523 OM_uint32 major; 1524 size_t len; 1525 u_char *p; 1526 int r; 1527 1528 if (!options.gss_authentication) 1529 fatal_f("GSSAPI authentication not enabled"); 1530 1531 if ((r = sshbuf_get_string(m, &p, &len)) != 0) 1532 fatal_fr(r, "parse"); 1533 goid.elements = p; 1534 goid.length = len; 1535 1536 major = ssh_gssapi_server_ctx(&gsscontext, &goid); 1537 1538 free(goid.elements); 1539 1540 sshbuf_reset(m); 1541 if ((r = sshbuf_put_u32(m, major)) != 0) 1542 fatal_fr(r, "assemble"); 1543 1544 mm_request_send(sock, MONITOR_ANS_GSSSETUP, m); 1545 1546 /* Now we have a context, enable the step */ 1547 monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 1); 1548 1549 return (0); 1550 } 1551 1552 int 1553 mm_answer_gss_accept_ctx(struct ssh *ssh, int sock, struct sshbuf *m) 1554 { 1555 gss_buffer_desc in; 1556 gss_buffer_desc out = GSS_C_EMPTY_BUFFER; 1557 OM_uint32 major, minor; 1558 OM_uint32 flags = 0; /* GSI needs this */ 1559 int r; 1560 1561 if (!options.gss_authentication) 1562 fatal_f("GSSAPI authentication not enabled"); 1563 1564 if ((r = ssh_gssapi_get_buffer_desc(m, &in)) != 0) 1565 fatal_fr(r, "ssh_gssapi_get_buffer_desc"); 1566 major = ssh_gssapi_accept_ctx(gsscontext, &in, &out, &flags); 1567 free(in.value); 1568 1569 sshbuf_reset(m); 1570 if ((r = sshbuf_put_u32(m, major)) != 0 || 1571 (r = sshbuf_put_string(m, out.value, out.length)) != 0 || 1572 (r = sshbuf_put_u32(m, flags)) != 0) 1573 fatal_fr(r, "assemble"); 1574 mm_request_send(sock, MONITOR_ANS_GSSSTEP, m); 1575 1576 gss_release_buffer(&minor, &out); 1577 1578 if (major == GSS_S_COMPLETE) { 1579 monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 0); 1580 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1); 1581 monitor_permit(mon_dispatch, MONITOR_REQ_GSSCHECKMIC, 1); 1582 } 1583 return (0); 1584 } 1585 1586 int 1587 mm_answer_gss_checkmic(struct ssh *ssh, int sock, struct sshbuf *m) 1588 { 1589 gss_buffer_desc gssbuf, mic; 1590 OM_uint32 ret; 1591 int r; 1592 1593 if (!options.gss_authentication) 1594 fatal_f("GSSAPI authentication not enabled"); 1595 1596 if ((r = ssh_gssapi_get_buffer_desc(m, &gssbuf)) != 0 || 1597 (r = ssh_gssapi_get_buffer_desc(m, &mic)) != 0) 1598 fatal_fr(r, "ssh_gssapi_get_buffer_desc"); 1599 1600 ret = ssh_gssapi_checkmic(gsscontext, &gssbuf, &mic); 1601 1602 free(gssbuf.value); 1603 free(mic.value); 1604 1605 sshbuf_reset(m); 1606 if ((r = sshbuf_put_u32(m, ret)) != 0) 1607 fatal_fr(r, "assemble"); 1608 1609 mm_request_send(sock, MONITOR_ANS_GSSCHECKMIC, m); 1610 1611 if (!GSS_ERROR(ret)) 1612 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1); 1613 1614 return (0); 1615 } 1616 1617 int 1618 mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m) 1619 { 1620 int r, authenticated; 1621 const char *displayname; 1622 1623 if (!options.gss_authentication) 1624 fatal_f("GSSAPI authentication not enabled"); 1625 1626 authenticated = authctxt->valid && ssh_gssapi_userok(authctxt->user); 1627 1628 sshbuf_reset(m); 1629 if ((r = sshbuf_put_u32(m, authenticated)) != 0) 1630 fatal_fr(r, "assemble"); 1631 1632 debug3_f("sending result %d", authenticated); 1633 mm_request_send(sock, MONITOR_ANS_GSSUSEROK, m); 1634 1635 auth_method = "gssapi-with-mic"; 1636 1637 if ((displayname = ssh_gssapi_displayname()) != NULL) 1638 auth2_record_info(authctxt, "%s", displayname); 1639 1640 /* Monitor loop will terminate if authenticated */ 1641 return (authenticated); 1642 } 1643 #endif /* GSSAPI */ 1644 1645