1 /* $OpenBSD: monitor.c,v 1.247 2024/12/03 22:30:03 jsg 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 #include "srclimit.h" 85 86 #ifdef GSSAPI 87 static Gssctxt *gsscontext = NULL; 88 #endif 89 90 /* Imports */ 91 extern ServerOptions options; 92 extern u_int utmp_len; 93 extern struct sshbuf *cfg; 94 extern struct sshbuf *loginmsg; 95 extern struct include_list includes; 96 extern struct sshauthopt *auth_opts; /* XXX move to permanent ssh->authctxt? */ 97 98 /* State exported from the child */ 99 static struct sshbuf *child_state; 100 101 /* Functions on the monitor that answer unprivileged requests */ 102 103 int mm_answer_moduli(struct ssh *, int, struct sshbuf *); 104 int mm_answer_sign(struct ssh *, int, struct sshbuf *); 105 int mm_answer_pwnamallow(struct ssh *, int, struct sshbuf *); 106 int mm_answer_auth2_read_banner(struct ssh *, int, struct sshbuf *); 107 int mm_answer_authserv(struct ssh *, int, struct sshbuf *); 108 int mm_answer_authpassword(struct ssh *, int, struct sshbuf *); 109 int mm_answer_bsdauthquery(struct ssh *, int, struct sshbuf *); 110 int mm_answer_bsdauthrespond(struct ssh *, int, struct sshbuf *); 111 int mm_answer_keyallowed(struct ssh *, int, struct sshbuf *); 112 int mm_answer_keyverify(struct ssh *, int, struct sshbuf *); 113 int mm_answer_pty(struct ssh *, int, struct sshbuf *); 114 int mm_answer_pty_cleanup(struct ssh *, int, struct sshbuf *); 115 int mm_answer_term(struct ssh *, int, struct sshbuf *); 116 int mm_answer_state(struct ssh *, int, struct sshbuf *); 117 118 #ifdef GSSAPI 119 int mm_answer_gss_setup_ctx(struct ssh *, int, struct sshbuf *); 120 int mm_answer_gss_accept_ctx(struct ssh *, int, struct sshbuf *); 121 int mm_answer_gss_userok(struct ssh *, int, struct sshbuf *); 122 int mm_answer_gss_checkmic(struct ssh *, int, struct sshbuf *); 123 #endif 124 125 static Authctxt *authctxt; 126 127 /* local state for key verify */ 128 static u_char *key_blob = NULL; 129 static size_t key_bloblen = 0; 130 static u_int key_blobtype = MM_NOKEY; 131 static struct sshauthopt *key_opts = NULL; 132 static char *hostbased_cuser = NULL; 133 static char *hostbased_chost = NULL; 134 static char *auth_method = "unknown"; 135 static char *auth_submethod = NULL; 136 static u_int session_id2_len = 0; 137 static u_char *session_id2 = NULL; 138 static pid_t monitor_child_pid; 139 int auth_attempted = 0; 140 141 struct mon_table { 142 enum monitor_reqtype type; 143 int flags; 144 int (*f)(struct ssh *, int, struct sshbuf *); 145 }; 146 147 #define MON_ISAUTH 0x0004 /* Required for Authentication */ 148 #define MON_AUTHDECIDE 0x0008 /* Decides Authentication */ 149 #define MON_ONCE 0x0010 /* Disable after calling */ 150 #define MON_ALOG 0x0020 /* Log auth attempt without authenticating */ 151 152 #define MON_AUTH (MON_ISAUTH|MON_AUTHDECIDE) 153 154 #define MON_PERMIT 0x1000 /* Request is permitted */ 155 156 static int monitor_read(struct ssh *, struct monitor *, struct mon_table *, 157 struct mon_table **); 158 static int monitor_read_log(struct monitor *); 159 160 struct mon_table mon_dispatch_proto20[] = { 161 {MONITOR_REQ_STATE, MON_ONCE, mm_answer_state}, 162 #ifdef WITH_OPENSSL 163 {MONITOR_REQ_MODULI, MON_ONCE, mm_answer_moduli}, 164 #endif 165 {MONITOR_REQ_SIGN, MON_ONCE, mm_answer_sign}, 166 {MONITOR_REQ_PWNAM, MON_ONCE, mm_answer_pwnamallow}, 167 {MONITOR_REQ_AUTHSERV, MON_ONCE, mm_answer_authserv}, 168 {MONITOR_REQ_AUTH2_READ_BANNER, MON_ONCE, mm_answer_auth2_read_banner}, 169 {MONITOR_REQ_AUTHPASSWORD, MON_AUTH, mm_answer_authpassword}, 170 {MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery}, 171 {MONITOR_REQ_BSDAUTHRESPOND, MON_AUTH, mm_answer_bsdauthrespond}, 172 {MONITOR_REQ_KEYALLOWED, MON_ISAUTH, mm_answer_keyallowed}, 173 {MONITOR_REQ_KEYVERIFY, MON_AUTH, mm_answer_keyverify}, 174 #ifdef GSSAPI 175 {MONITOR_REQ_GSSSETUP, MON_ISAUTH, mm_answer_gss_setup_ctx}, 176 {MONITOR_REQ_GSSSTEP, 0, mm_answer_gss_accept_ctx}, 177 {MONITOR_REQ_GSSUSEROK, MON_ONCE|MON_AUTHDECIDE, mm_answer_gss_userok}, 178 {MONITOR_REQ_GSSCHECKMIC, MON_ONCE, mm_answer_gss_checkmic}, 179 #endif 180 {0, 0, NULL} 181 }; 182 183 struct mon_table mon_dispatch_postauth20[] = { 184 {MONITOR_REQ_STATE, MON_ONCE, mm_answer_state}, 185 #ifdef WITH_OPENSSL 186 {MONITOR_REQ_MODULI, 0, mm_answer_moduli}, 187 #endif 188 {MONITOR_REQ_SIGN, 0, mm_answer_sign}, 189 {MONITOR_REQ_PTY, 0, mm_answer_pty}, 190 {MONITOR_REQ_PTYCLEANUP, 0, mm_answer_pty_cleanup}, 191 {MONITOR_REQ_TERM, 0, mm_answer_term}, 192 {0, 0, NULL} 193 }; 194 195 struct mon_table *mon_dispatch; 196 197 /* Specifies if a certain message is allowed at the moment */ 198 static void 199 monitor_permit(struct mon_table *ent, enum monitor_reqtype type, int permit) 200 { 201 while (ent->f != NULL) { 202 if (ent->type == type) { 203 ent->flags &= ~MON_PERMIT; 204 ent->flags |= permit ? MON_PERMIT : 0; 205 return; 206 } 207 ent++; 208 } 209 } 210 211 static void 212 monitor_permit_authentications(int permit) 213 { 214 struct mon_table *ent = mon_dispatch; 215 216 while (ent->f != NULL) { 217 if (ent->flags & MON_AUTH) { 218 ent->flags &= ~MON_PERMIT; 219 ent->flags |= permit ? MON_PERMIT : 0; 220 } 221 ent++; 222 } 223 } 224 225 void 226 monitor_child_preauth(struct ssh *ssh, struct monitor *pmonitor) 227 { 228 struct mon_table *ent; 229 int authenticated = 0, partial = 0; 230 231 debug3("preauth child monitor started"); 232 233 if (pmonitor->m_recvfd >= 0) 234 close(pmonitor->m_recvfd); 235 if (pmonitor->m_log_sendfd >= 0) 236 close(pmonitor->m_log_sendfd); 237 pmonitor->m_log_sendfd = pmonitor->m_recvfd = -1; 238 239 authctxt = (Authctxt *)ssh->authctxt; 240 memset(authctxt, 0, sizeof(*authctxt)); 241 ssh->authctxt = authctxt; 242 243 mon_dispatch = mon_dispatch_proto20; 244 /* Permit requests for state, moduli and signatures */ 245 monitor_permit(mon_dispatch, MONITOR_REQ_STATE, 1); 246 monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); 247 monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); 248 249 /* The first few requests do not require asynchronous access */ 250 while (!authenticated) { 251 partial = 0; 252 auth_method = "unknown"; 253 auth_submethod = NULL; 254 auth2_authctxt_reset_info(authctxt); 255 256 authenticated = (monitor_read(ssh, pmonitor, 257 mon_dispatch, &ent) == 1); 258 259 /* Record that auth was attempted to set exit status later */ 260 if ((ent->flags & MON_AUTH) != 0) 261 auth_attempted = 1; 262 263 /* Special handling for multiple required authentications */ 264 if (options.num_auth_methods != 0) { 265 if (authenticated && 266 !auth2_update_methods_lists(authctxt, 267 auth_method, auth_submethod)) { 268 debug3_f("method %s: partial", auth_method); 269 authenticated = 0; 270 partial = 1; 271 } 272 } 273 274 if (authenticated) { 275 if (!(ent->flags & MON_AUTHDECIDE)) 276 fatal_f("unexpected authentication from %d", 277 ent->type); 278 if (authctxt->pw->pw_uid == 0 && 279 !auth_root_allowed(ssh, auth_method)) 280 authenticated = 0; 281 } 282 if (ent->flags & (MON_AUTHDECIDE|MON_ALOG)) { 283 auth_log(ssh, authenticated, partial, 284 auth_method, auth_submethod); 285 if (!partial && !authenticated) 286 authctxt->failures++; 287 if (authenticated || partial) { 288 auth2_update_session_info(authctxt, 289 auth_method, auth_submethod); 290 } 291 } 292 if (authctxt->failures > options.max_authtries) { 293 /* Shouldn't happen */ 294 fatal_f("privsep child made too many authentication " 295 "attempts"); 296 } 297 } 298 299 if (!authctxt->valid) 300 fatal_f("authenticated invalid user"); 301 if (strcmp(auth_method, "unknown") == 0) 302 fatal_f("authentication method name unknown"); 303 304 debug_f("user %s authenticated by privileged process", authctxt->user); 305 auth_attempted = 0; 306 ssh->authctxt = NULL; 307 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 308 309 mm_get_keystate(ssh, pmonitor); 310 311 /* Drain any buffered messages from the child */ 312 while (pmonitor->m_log_recvfd != -1 && monitor_read_log(pmonitor) == 0) 313 ; 314 315 if (pmonitor->m_recvfd >= 0) 316 close(pmonitor->m_recvfd); 317 if (pmonitor->m_log_sendfd >= 0) 318 close(pmonitor->m_log_sendfd); 319 pmonitor->m_sendfd = pmonitor->m_log_recvfd = -1; 320 } 321 322 static void 323 monitor_set_child_handler(pid_t pid) 324 { 325 monitor_child_pid = pid; 326 } 327 328 static void 329 monitor_child_handler(int sig) 330 { 331 kill(monitor_child_pid, sig); 332 } 333 334 void 335 monitor_child_postauth(struct ssh *ssh, struct monitor *pmonitor) 336 { 337 close(pmonitor->m_recvfd); 338 pmonitor->m_recvfd = -1; 339 340 monitor_set_child_handler(pmonitor->m_pid); 341 ssh_signal(SIGHUP, &monitor_child_handler); 342 ssh_signal(SIGTERM, &monitor_child_handler); 343 ssh_signal(SIGINT, &monitor_child_handler); 344 345 mon_dispatch = mon_dispatch_postauth20; 346 347 /* Permit requests for moduli and signatures */ 348 monitor_permit(mon_dispatch, MONITOR_REQ_STATE, 1); 349 monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); 350 monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); 351 monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1); 352 353 if (auth_opts->permit_pty_flag) { 354 monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1); 355 monitor_permit(mon_dispatch, MONITOR_REQ_PTYCLEANUP, 1); 356 } 357 358 for (;;) 359 monitor_read(ssh, pmonitor, mon_dispatch, NULL); 360 } 361 362 static int 363 monitor_read_log(struct monitor *pmonitor) 364 { 365 struct sshbuf *logmsg; 366 u_int len, level, forced; 367 char *msg; 368 u_char *p; 369 int r; 370 371 if ((logmsg = sshbuf_new()) == NULL) 372 fatal_f("sshbuf_new"); 373 374 /* Read length */ 375 if ((r = sshbuf_reserve(logmsg, 4, &p)) != 0) 376 fatal_fr(r, "reserve len"); 377 if (atomicio(read, pmonitor->m_log_recvfd, p, 4) != 4) { 378 if (errno == EPIPE) { 379 sshbuf_free(logmsg); 380 debug_f("child log fd closed"); 381 close(pmonitor->m_log_recvfd); 382 pmonitor->m_log_recvfd = -1; 383 return -1; 384 } 385 fatal_f("log fd read: %s", strerror(errno)); 386 } 387 if ((r = sshbuf_get_u32(logmsg, &len)) != 0) 388 fatal_fr(r, "parse len"); 389 if (len <= 4 || len > 8192) 390 fatal_f("invalid log message length %u", len); 391 392 /* Read severity, message */ 393 sshbuf_reset(logmsg); 394 if ((r = sshbuf_reserve(logmsg, len, &p)) != 0) 395 fatal_fr(r, "reserve msg"); 396 if (atomicio(read, pmonitor->m_log_recvfd, p, len) != len) 397 fatal_f("log fd read: %s", strerror(errno)); 398 if ((r = sshbuf_get_u32(logmsg, &level)) != 0 || 399 (r = sshbuf_get_u32(logmsg, &forced)) != 0 || 400 (r = sshbuf_get_cstring(logmsg, &msg, NULL)) != 0) 401 fatal_fr(r, "parse"); 402 403 /* Log it */ 404 if (log_level_name(level) == NULL) 405 fatal_f("invalid log level %u (corrupted message?)", level); 406 sshlogdirect(level, forced, "%s [%s]", msg, 407 mon_dispatch == mon_dispatch_postauth20 ? "postauth" : "preauth"); 408 409 sshbuf_free(logmsg); 410 free(msg); 411 412 return 0; 413 } 414 415 static int 416 monitor_read(struct ssh *ssh, struct monitor *pmonitor, struct mon_table *ent, 417 struct mon_table **pent) 418 { 419 struct sshbuf *m; 420 int r, ret; 421 u_char type; 422 struct pollfd pfd[2]; 423 424 for (;;) { 425 memset(&pfd, 0, sizeof(pfd)); 426 pfd[0].fd = pmonitor->m_sendfd; 427 pfd[0].events = POLLIN; 428 pfd[1].fd = pmonitor->m_log_recvfd; 429 pfd[1].events = pfd[1].fd == -1 ? 0 : POLLIN; 430 if (poll(pfd, pfd[1].fd == -1 ? 1 : 2, -1) == -1) { 431 if (errno == EINTR || errno == EAGAIN) 432 continue; 433 fatal_f("poll: %s", strerror(errno)); 434 } 435 if (pfd[1].revents) { 436 /* 437 * Drain all log messages before processing next 438 * monitor request. 439 */ 440 monitor_read_log(pmonitor); 441 continue; 442 } 443 if (pfd[0].revents) 444 break; /* Continues below */ 445 } 446 447 if ((m = sshbuf_new()) == NULL) 448 fatal_f("sshbuf_new"); 449 450 mm_request_receive(pmonitor->m_sendfd, m); 451 if ((r = sshbuf_get_u8(m, &type)) != 0) 452 fatal_fr(r, "parse type"); 453 454 debug3_f("checking request %d", type); 455 456 while (ent->f != NULL) { 457 if (ent->type == type) 458 break; 459 ent++; 460 } 461 462 if (ent->f != NULL) { 463 if (!(ent->flags & MON_PERMIT)) 464 fatal_f("unpermitted request %d", type); 465 ret = (*ent->f)(ssh, pmonitor->m_sendfd, m); 466 sshbuf_free(m); 467 468 /* The child may use this request only once, disable it */ 469 if (ent->flags & MON_ONCE) { 470 debug2_f("%d used once, disabling now", type); 471 ent->flags &= ~MON_PERMIT; 472 } 473 474 if (pent != NULL) 475 *pent = ent; 476 477 return ret; 478 } 479 480 fatal_f("unsupported request: %d", type); 481 482 /* NOTREACHED */ 483 return (-1); 484 } 485 486 /* allowed key state */ 487 static int 488 monitor_allowed_key(const u_char *blob, u_int bloblen) 489 { 490 /* make sure key is allowed */ 491 if (key_blob == NULL || key_bloblen != bloblen || 492 timingsafe_bcmp(key_blob, blob, key_bloblen)) 493 return (0); 494 return (1); 495 } 496 497 static void 498 monitor_reset_key_state(void) 499 { 500 /* reset state */ 501 free(key_blob); 502 free(hostbased_cuser); 503 free(hostbased_chost); 504 sshauthopt_free(key_opts); 505 key_blob = NULL; 506 key_bloblen = 0; 507 key_blobtype = MM_NOKEY; 508 key_opts = NULL; 509 hostbased_cuser = NULL; 510 hostbased_chost = NULL; 511 } 512 513 int 514 mm_answer_state(struct ssh *ssh, int sock, struct sshbuf *m) 515 { 516 struct sshbuf *inc = NULL, *hostkeys = NULL; 517 struct sshbuf *opts = NULL, *confdata = NULL; 518 struct include_item *item = NULL; 519 int postauth; 520 int r; 521 522 sshbuf_reset(m); 523 524 debug_f("config len %zu", sshbuf_len(cfg)); 525 526 if ((m = sshbuf_new()) == NULL || 527 (inc = sshbuf_new()) == NULL || 528 (opts = sshbuf_new()) == NULL || 529 (confdata = sshbuf_new()) == NULL) 530 fatal_f("sshbuf_new failed"); 531 532 /* XXX unnecessary? */ 533 /* pack includes into a string */ 534 TAILQ_FOREACH(item, &includes, entry) { 535 if ((r = sshbuf_put_cstring(inc, item->selector)) != 0 || 536 (r = sshbuf_put_cstring(inc, item->filename)) != 0 || 537 (r = sshbuf_put_stringb(inc, item->contents)) != 0) 538 fatal_fr(r, "compose includes"); 539 } 540 541 hostkeys = pack_hostkeys(); 542 543 /* 544 * Protocol from monitor to unpriv privsep process: 545 * string configuration 546 * uint64 timing_secret XXX move delays to monitor and remove 547 * string host_keys[] { 548 * string public_key 549 * string certificate 550 * } 551 * string server_banner 552 * string client_banner 553 * string included_files[] { 554 * string selector 555 * string filename 556 * string contents 557 * } 558 * string configuration_data (postauth) 559 * string keystate (postauth) 560 * string authenticated_user (postauth) 561 * string session_info (postauth) 562 * string authopts (postauth) 563 */ 564 if ((r = sshbuf_put_stringb(m, cfg)) != 0 || 565 (r = sshbuf_put_u64(m, options.timing_secret)) != 0 || 566 (r = sshbuf_put_stringb(m, hostkeys)) != 0 || 567 (r = sshbuf_put_stringb(m, ssh->kex->server_version)) != 0 || 568 (r = sshbuf_put_stringb(m, ssh->kex->client_version)) != 0 || 569 (r = sshbuf_put_stringb(m, inc)) != 0) 570 fatal_fr(r, "compose config"); 571 572 postauth = (authctxt && authctxt->pw && authctxt->authenticated); 573 if (postauth) { 574 /* XXX shouldn't be reachable */ 575 fatal_f("internal error: called in postauth"); 576 } 577 578 sshbuf_free(inc); 579 sshbuf_free(opts); 580 sshbuf_free(confdata); 581 582 mm_request_send(sock, MONITOR_ANS_STATE, m); 583 584 debug3_f("done"); 585 586 return (0); 587 } 588 589 #ifdef WITH_OPENSSL 590 int 591 mm_answer_moduli(struct ssh *ssh, int sock, struct sshbuf *m) 592 { 593 DH *dh; 594 const BIGNUM *dh_p, *dh_g; 595 int r; 596 u_int min, want, max; 597 598 if ((r = sshbuf_get_u32(m, &min)) != 0 || 599 (r = sshbuf_get_u32(m, &want)) != 0 || 600 (r = sshbuf_get_u32(m, &max)) != 0) 601 fatal_fr(r, "parse"); 602 603 debug3_f("got parameters: %d %d %d", min, want, max); 604 /* We need to check here, too, in case the child got corrupted */ 605 if (max < min || want < min || max < want) 606 fatal_f("bad parameters: %d %d %d", min, want, max); 607 608 sshbuf_reset(m); 609 610 dh = choose_dh(min, want, max); 611 if (dh == NULL) { 612 if ((r = sshbuf_put_u8(m, 0)) != 0) 613 fatal_fr(r, "assemble empty"); 614 return (0); 615 } else { 616 /* Send first bignum */ 617 DH_get0_pqg(dh, &dh_p, NULL, &dh_g); 618 if ((r = sshbuf_put_u8(m, 1)) != 0 || 619 (r = sshbuf_put_bignum2(m, dh_p)) != 0 || 620 (r = sshbuf_put_bignum2(m, dh_g)) != 0) 621 fatal_fr(r, "assemble"); 622 623 DH_free(dh); 624 } 625 mm_request_send(sock, MONITOR_ANS_MODULI, m); 626 return (0); 627 } 628 #endif 629 630 int 631 mm_answer_sign(struct ssh *ssh, int sock, struct sshbuf *m) 632 { 633 extern int auth_sock; /* XXX move to state struct? */ 634 struct sshkey *pubkey, *key; 635 struct sshbuf *sigbuf = NULL; 636 u_char *p = NULL, *signature = NULL; 637 char *alg = NULL; 638 size_t datlen, siglen; 639 int r, is_proof = 0, keyid; 640 u_int compat; 641 const char proof_req[] = "hostkeys-prove-00@openssh.com"; 642 643 debug3_f("entering"); 644 645 if ((r = sshkey_froms(m, &pubkey)) != 0 || 646 (r = sshbuf_get_string(m, &p, &datlen)) != 0 || 647 (r = sshbuf_get_cstring(m, &alg, NULL)) != 0 || 648 (r = sshbuf_get_u32(m, &compat)) != 0) 649 fatal_fr(r, "parse"); 650 651 if ((keyid = get_hostkey_index(pubkey, 1, ssh)) == -1) 652 fatal_f("unknown hostkey"); 653 debug_f("hostkey %s index %d", sshkey_ssh_name(pubkey), keyid); 654 sshkey_free(pubkey); 655 656 /* 657 * Supported KEX types use SHA1 (20 bytes), SHA256 (32 bytes), 658 * SHA384 (48 bytes) and SHA512 (64 bytes). 659 * 660 * Otherwise, verify the signature request is for a hostkey 661 * proof. 662 * 663 * XXX perform similar check for KEX signature requests too? 664 * it's not trivial, since what is signed is the hash, rather 665 * than the full kex structure... 666 */ 667 if (datlen != 20 && datlen != 32 && datlen != 48 && datlen != 64) { 668 /* 669 * Construct expected hostkey proof and compare it to what 670 * the client sent us. 671 */ 672 if (session_id2_len == 0) /* hostkeys is never first */ 673 fatal_f("bad data length: %zu", datlen); 674 if ((key = get_hostkey_public_by_index(keyid, ssh)) == NULL) 675 fatal_f("no hostkey for index %d", keyid); 676 if ((sigbuf = sshbuf_new()) == NULL) 677 fatal_f("sshbuf_new"); 678 if ((r = sshbuf_put_cstring(sigbuf, proof_req)) != 0 || 679 (r = sshbuf_put_string(sigbuf, session_id2, 680 session_id2_len)) != 0 || 681 (r = sshkey_puts(key, sigbuf)) != 0) 682 fatal_fr(r, "assemble private key proof"); 683 if (datlen != sshbuf_len(sigbuf) || 684 memcmp(p, sshbuf_ptr(sigbuf), sshbuf_len(sigbuf)) != 0) 685 fatal_f("bad data length: %zu, hostkey proof len %zu", 686 datlen, sshbuf_len(sigbuf)); 687 sshbuf_free(sigbuf); 688 is_proof = 1; 689 } 690 691 /* save session id, it will be passed on the first call */ 692 if (session_id2_len == 0) { 693 session_id2_len = datlen; 694 session_id2 = xmalloc(session_id2_len); 695 memcpy(session_id2, p, session_id2_len); 696 } 697 698 if ((key = get_hostkey_by_index(keyid)) != NULL) { 699 if ((r = sshkey_sign(key, &signature, &siglen, p, datlen, alg, 700 options.sk_provider, NULL, compat)) != 0) 701 fatal_fr(r, "sign"); 702 } else if ((key = get_hostkey_public_by_index(keyid, ssh)) != NULL && 703 auth_sock > 0) { 704 if ((r = ssh_agent_sign(auth_sock, key, &signature, &siglen, 705 p, datlen, alg, compat)) != 0) 706 fatal_fr(r, "agent sign"); 707 } else 708 fatal_f("no hostkey from index %d", keyid); 709 710 debug3_f("%s %s signature len=%zu", alg, 711 is_proof ? "hostkey proof" : "KEX", siglen); 712 713 sshbuf_reset(m); 714 if ((r = sshbuf_put_string(m, signature, siglen)) != 0) 715 fatal_fr(r, "assemble"); 716 717 free(alg); 718 free(p); 719 free(signature); 720 721 mm_request_send(sock, MONITOR_ANS_SIGN, m); 722 723 /* Turn on permissions for getpwnam */ 724 monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1); 725 726 return (0); 727 } 728 729 #define PUTPW(b, id) \ 730 do { \ 731 if ((r = sshbuf_put_string(b, \ 732 &pwent->id, sizeof(pwent->id))) != 0) \ 733 fatal_fr(r, "assemble %s", #id); \ 734 } while (0) 735 736 void 737 mm_encode_server_options(struct sshbuf *m) 738 { 739 int r; 740 u_int i; 741 742 /* XXX this leaks raw pointers to the unpriv child processes */ 743 if ((r = sshbuf_put_string(m, &options, sizeof(options))) != 0) 744 fatal_fr(r, "assemble options"); 745 746 #define M_CP_STROPT(x) do { \ 747 if (options.x != NULL && \ 748 (r = sshbuf_put_cstring(m, options.x)) != 0) \ 749 fatal_fr(r, "assemble %s", #x); \ 750 } while (0) 751 #define M_CP_STRARRAYOPT(x, nx) do { \ 752 for (i = 0; i < options.nx; i++) { \ 753 if ((r = sshbuf_put_cstring(m, options.x[i])) != 0) \ 754 fatal_fr(r, "assemble %s", #x); \ 755 } \ 756 } while (0) 757 /* See comment in servconf.h */ 758 COPY_MATCH_STRING_OPTS(); 759 #undef M_CP_STROPT 760 #undef M_CP_STRARRAYOPT 761 } 762 763 /* Retrieves the password entry and also checks if the user is permitted */ 764 int 765 mm_answer_pwnamallow(struct ssh *ssh, int sock, struct sshbuf *m) 766 { 767 struct passwd *pwent; 768 int r, allowed = 0; 769 770 debug3_f("entering"); 771 772 if (authctxt->attempt++ != 0) 773 fatal_f("multiple attempts for getpwnam"); 774 775 if ((r = sshbuf_get_cstring(m, &authctxt->user, NULL)) != 0) 776 fatal_fr(r, "parse"); 777 778 pwent = getpwnamallow(ssh, authctxt->user); 779 780 setproctitle("%s [priv]", pwent ? authctxt->user : "unknown"); 781 782 sshbuf_reset(m); 783 784 if (pwent == NULL) { 785 if ((r = sshbuf_put_u8(m, 0)) != 0) 786 fatal_fr(r, "assemble fakepw"); 787 authctxt->pw = fakepw(); 788 goto out; 789 } 790 791 allowed = 1; 792 authctxt->pw = pwent; 793 authctxt->valid = 1; 794 795 /* XXX send fake class/dir/shell, etc. */ 796 if ((r = sshbuf_put_u8(m, 1)) != 0) 797 fatal_fr(r, "assemble ok"); 798 PUTPW(m, pw_uid); 799 PUTPW(m, pw_gid); 800 PUTPW(m, pw_change); 801 PUTPW(m, pw_expire); 802 if ((r = sshbuf_put_cstring(m, pwent->pw_name)) != 0 || 803 (r = sshbuf_put_cstring(m, "*")) != 0 || 804 (r = sshbuf_put_cstring(m, pwent->pw_gecos)) != 0 || 805 (r = sshbuf_put_cstring(m, pwent->pw_class)) != 0 || 806 (r = sshbuf_put_cstring(m, pwent->pw_dir)) != 0 || 807 (r = sshbuf_put_cstring(m, pwent->pw_shell)) != 0) 808 fatal_fr(r, "assemble pw"); 809 810 out: 811 ssh_packet_set_log_preamble(ssh, "%suser %s", 812 authctxt->valid ? "authenticating" : "invalid ", authctxt->user); 813 814 if (options.refuse_connection) { 815 logit("administratively prohibited connection for " 816 "%s%s from %.128s port %d", 817 authctxt->valid ? "" : "invalid user ", 818 authctxt->user, ssh_remote_ipaddr(ssh), 819 ssh_remote_port(ssh)); 820 cleanup_exit(EXIT_CONFIG_REFUSED); 821 } 822 823 /* Send active options to unpriv */ 824 mm_encode_server_options(m); 825 826 /* Create valid auth method lists */ 827 if (auth2_setup_methods_lists(authctxt) != 0) { 828 /* 829 * The monitor will continue long enough to let the child 830 * run to its packet_disconnect(), but it must not allow any 831 * authentication to succeed. 832 */ 833 debug_f("no valid authentication method lists"); 834 } 835 836 debug3_f("sending MONITOR_ANS_PWNAM: %d", allowed); 837 mm_request_send(sock, MONITOR_ANS_PWNAM, m); 838 839 /* Allow service/style information on the auth context */ 840 monitor_permit(mon_dispatch, MONITOR_REQ_AUTHSERV, 1); 841 monitor_permit(mon_dispatch, MONITOR_REQ_AUTH2_READ_BANNER, 1); 842 843 return (0); 844 } 845 846 int mm_answer_auth2_read_banner(struct ssh *ssh, int sock, struct sshbuf *m) 847 { 848 char *banner; 849 int r; 850 851 sshbuf_reset(m); 852 banner = auth2_read_banner(); 853 if ((r = sshbuf_put_cstring(m, banner != NULL ? banner : "")) != 0) 854 fatal_fr(r, "assemble"); 855 mm_request_send(sock, MONITOR_ANS_AUTH2_READ_BANNER, m); 856 free(banner); 857 858 return (0); 859 } 860 861 int 862 mm_answer_authserv(struct ssh *ssh, int sock, struct sshbuf *m) 863 { 864 int r; 865 866 monitor_permit_authentications(1); 867 868 if ((r = sshbuf_get_cstring(m, &authctxt->service, NULL)) != 0 || 869 (r = sshbuf_get_cstring(m, &authctxt->style, NULL)) != 0) 870 fatal_fr(r, "parse"); 871 debug3_f("service=%s, style=%s", authctxt->service, authctxt->style); 872 873 if (strlen(authctxt->style) == 0) { 874 free(authctxt->style); 875 authctxt->style = NULL; 876 } 877 878 return (0); 879 } 880 881 int 882 mm_answer_authpassword(struct ssh *ssh, int sock, struct sshbuf *m) 883 { 884 static int call_count; 885 char *passwd; 886 int r, authenticated; 887 size_t plen; 888 889 if (!options.password_authentication) 890 fatal_f("password authentication not enabled"); 891 if ((r = sshbuf_get_cstring(m, &passwd, &plen)) != 0) 892 fatal_fr(r, "parse"); 893 /* Only authenticate if the context is valid */ 894 authenticated = options.password_authentication && 895 auth_password(ssh, passwd); 896 freezero(passwd, plen); 897 898 sshbuf_reset(m); 899 if ((r = sshbuf_put_u32(m, authenticated)) != 0) 900 fatal_fr(r, "assemble"); 901 902 debug3_f("sending result %d", authenticated); 903 mm_request_send(sock, MONITOR_ANS_AUTHPASSWORD, m); 904 905 call_count++; 906 if (plen == 0 && call_count == 1) 907 auth_method = "none"; 908 else 909 auth_method = "password"; 910 911 /* Causes monitor loop to terminate if authenticated */ 912 return (authenticated); 913 } 914 915 int 916 mm_answer_bsdauthquery(struct ssh *ssh, int sock, struct sshbuf *m) 917 { 918 char *name, *infotxt; 919 u_int numprompts, *echo_on, success; 920 char **prompts; 921 int r; 922 923 if (!options.kbd_interactive_authentication) 924 fatal_f("kbd-int authentication not enabled"); 925 success = bsdauth_query(authctxt, &name, &infotxt, &numprompts, 926 &prompts, &echo_on) < 0 ? 0 : 1; 927 928 sshbuf_reset(m); 929 if ((r = sshbuf_put_u32(m, success)) != 0) 930 fatal_fr(r, "assemble"); 931 if (success) { 932 if ((r = sshbuf_put_cstring(m, prompts[0])) != 0) 933 fatal_fr(r, "assemble prompt"); 934 } 935 936 debug3_f("sending challenge success: %u", success); 937 mm_request_send(sock, MONITOR_ANS_BSDAUTHQUERY, m); 938 939 if (success) { 940 free(name); 941 free(infotxt); 942 free(prompts); 943 free(echo_on); 944 } 945 946 return (0); 947 } 948 949 int 950 mm_answer_bsdauthrespond(struct ssh *ssh, int sock, struct sshbuf *m) 951 { 952 char *response; 953 int r, authok; 954 955 if (!options.kbd_interactive_authentication) 956 fatal_f("kbd-int authentication not enabled"); 957 if (authctxt->as == NULL) 958 fatal_f("no bsd auth session"); 959 960 if ((r = sshbuf_get_cstring(m, &response, NULL)) != 0) 961 fatal_fr(r, "parse"); 962 authok = options.kbd_interactive_authentication && 963 auth_userresponse(authctxt->as, response, 0); 964 authctxt->as = NULL; 965 debug3_f("<%s> = <%d>", response, authok); 966 free(response); 967 968 sshbuf_reset(m); 969 if ((r = sshbuf_put_u32(m, authok)) != 0) 970 fatal_fr(r, "assemble"); 971 972 debug3_f("sending authenticated: %d", authok); 973 mm_request_send(sock, MONITOR_ANS_BSDAUTHRESPOND, m); 974 975 auth_method = "keyboard-interactive"; 976 auth_submethod = "bsdauth"; 977 978 return (authok != 0); 979 } 980 981 /* 982 * Check that the key type appears in the supplied pattern list, ignoring 983 * mismatches in the signature algorithm. (Signature algorithm checks are 984 * performed in the unprivileged authentication code). 985 * Returns 1 on success, 0 otherwise. 986 */ 987 static int 988 key_base_type_match(const char *method, const struct sshkey *key, 989 const char *list) 990 { 991 char *s, *l, *ol = xstrdup(list); 992 int found = 0; 993 994 l = ol; 995 for ((s = strsep(&l, ",")); s && *s != '\0'; (s = strsep(&l, ","))) { 996 if (sshkey_type_from_name(s) == key->type) { 997 found = 1; 998 break; 999 } 1000 } 1001 if (!found) { 1002 error("%s key type %s is not in permitted list %s", method, 1003 sshkey_ssh_name(key), list); 1004 } 1005 1006 free(ol); 1007 return found; 1008 } 1009 1010 int 1011 mm_answer_keyallowed(struct ssh *ssh, int sock, struct sshbuf *m) 1012 { 1013 struct sshkey *key = NULL; 1014 char *cuser, *chost; 1015 u_int pubkey_auth_attempt; 1016 u_int type = 0; 1017 int r, allowed = 0; 1018 struct sshauthopt *opts = NULL; 1019 1020 debug3_f("entering"); 1021 if ((r = sshbuf_get_u32(m, &type)) != 0 || 1022 (r = sshbuf_get_cstring(m, &cuser, NULL)) != 0 || 1023 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 || 1024 (r = sshkey_froms(m, &key)) != 0 || 1025 (r = sshbuf_get_u32(m, &pubkey_auth_attempt)) != 0) 1026 fatal_fr(r, "parse"); 1027 1028 if (key != NULL && authctxt->valid) { 1029 switch (type) { 1030 case MM_USERKEY: 1031 auth_method = "publickey"; 1032 if (!options.pubkey_authentication) 1033 break; 1034 if (auth2_key_already_used(authctxt, key)) 1035 break; 1036 if (!key_base_type_match(auth_method, key, 1037 options.pubkey_accepted_algos)) 1038 break; 1039 allowed = user_key_allowed(ssh, authctxt->pw, key, 1040 pubkey_auth_attempt, &opts); 1041 break; 1042 case MM_HOSTKEY: 1043 auth_method = "hostbased"; 1044 if (!options.hostbased_authentication) 1045 break; 1046 if (auth2_key_already_used(authctxt, key)) 1047 break; 1048 if (!key_base_type_match(auth_method, key, 1049 options.hostbased_accepted_algos)) 1050 break; 1051 allowed = hostbased_key_allowed(ssh, authctxt->pw, 1052 cuser, chost, key); 1053 auth2_record_info(authctxt, 1054 "client user \"%.100s\", client host \"%.100s\"", 1055 cuser, chost); 1056 break; 1057 default: 1058 fatal_f("unknown key type %u", type); 1059 break; 1060 } 1061 } 1062 1063 debug3_f("%s authentication%s: %s key is %s", auth_method, 1064 pubkey_auth_attempt ? "" : " test", 1065 (key == NULL || !authctxt->valid) ? "invalid" : sshkey_type(key), 1066 allowed ? "allowed" : "not allowed"); 1067 1068 auth2_record_key(authctxt, 0, key); 1069 1070 /* clear temporarily storage (used by verify) */ 1071 monitor_reset_key_state(); 1072 1073 if (allowed) { 1074 /* Save temporarily for comparison in verify */ 1075 if ((r = sshkey_to_blob(key, &key_blob, &key_bloblen)) != 0) 1076 fatal_fr(r, "sshkey_to_blob"); 1077 key_blobtype = type; 1078 key_opts = opts; 1079 hostbased_cuser = cuser; 1080 hostbased_chost = chost; 1081 } else { 1082 /* Log failed attempt */ 1083 auth_log(ssh, 0, 0, auth_method, NULL); 1084 free(cuser); 1085 free(chost); 1086 } 1087 sshkey_free(key); 1088 1089 sshbuf_reset(m); 1090 if ((r = sshbuf_put_u32(m, allowed)) != 0) 1091 fatal_fr(r, "assemble"); 1092 if (opts != NULL && (r = sshauthopt_serialise(opts, m, 1)) != 0) 1093 fatal_fr(r, "sshauthopt_serialise"); 1094 mm_request_send(sock, MONITOR_ANS_KEYALLOWED, m); 1095 1096 if (!allowed) 1097 sshauthopt_free(opts); 1098 1099 return (0); 1100 } 1101 1102 static int 1103 monitor_valid_userblob(struct ssh *ssh, const u_char *data, u_int datalen) 1104 { 1105 struct sshbuf *b; 1106 struct sshkey *hostkey = NULL; 1107 const u_char *p; 1108 char *userstyle, *cp; 1109 size_t len; 1110 u_char type; 1111 int hostbound = 0, r, fail = 0; 1112 1113 if ((b = sshbuf_from(data, datalen)) == NULL) 1114 fatal_f("sshbuf_from"); 1115 1116 if (ssh->compat & SSH_OLD_SESSIONID) { 1117 p = sshbuf_ptr(b); 1118 len = sshbuf_len(b); 1119 if ((session_id2 == NULL) || 1120 (len < session_id2_len) || 1121 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) 1122 fail++; 1123 if ((r = sshbuf_consume(b, session_id2_len)) != 0) 1124 fatal_fr(r, "consume"); 1125 } else { 1126 if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0) 1127 fatal_fr(r, "parse sessionid"); 1128 if ((session_id2 == NULL) || 1129 (len != session_id2_len) || 1130 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) 1131 fail++; 1132 } 1133 if ((r = sshbuf_get_u8(b, &type)) != 0) 1134 fatal_fr(r, "parse type"); 1135 if (type != SSH2_MSG_USERAUTH_REQUEST) 1136 fail++; 1137 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1138 fatal_fr(r, "parse userstyle"); 1139 xasprintf(&userstyle, "%s%s%s", authctxt->user, 1140 authctxt->style ? ":" : "", 1141 authctxt->style ? authctxt->style : ""); 1142 if (strcmp(userstyle, cp) != 0) { 1143 logit("wrong user name passed to monitor: " 1144 "expected %s != %.100s", userstyle, cp); 1145 fail++; 1146 } 1147 free(userstyle); 1148 free(cp); 1149 if ((r = sshbuf_skip_string(b)) != 0 || /* service */ 1150 (r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1151 fatal_fr(r, "parse method"); 1152 if (strcmp("publickey", cp) != 0) { 1153 if (strcmp("publickey-hostbound-v00@openssh.com", cp) == 0) 1154 hostbound = 1; 1155 else 1156 fail++; 1157 } 1158 free(cp); 1159 if ((r = sshbuf_get_u8(b, &type)) != 0) 1160 fatal_fr(r, "parse pktype"); 1161 if (type == 0) 1162 fail++; 1163 if ((r = sshbuf_skip_string(b)) != 0 || /* pkalg */ 1164 (r = sshbuf_skip_string(b)) != 0 || /* pkblob */ 1165 (hostbound && (r = sshkey_froms(b, &hostkey)) != 0)) 1166 fatal_fr(r, "parse pk"); 1167 if (sshbuf_len(b) != 0) 1168 fail++; 1169 sshbuf_free(b); 1170 if (hostkey != NULL) { 1171 /* 1172 * Ensure this is actually one of our hostkeys; unfortunately 1173 * can't check ssh->kex->initial_hostkey directly at this point 1174 * as packet state has not yet been exported to monitor. 1175 */ 1176 if (get_hostkey_index(hostkey, 1, ssh) == -1) 1177 fatal_f("hostbound hostkey does not match"); 1178 sshkey_free(hostkey); 1179 } 1180 return (fail == 0); 1181 } 1182 1183 static int 1184 monitor_valid_hostbasedblob(const u_char *data, u_int datalen, 1185 const char *cuser, const char *chost) 1186 { 1187 struct sshbuf *b; 1188 const u_char *p; 1189 char *cp, *userstyle; 1190 size_t len; 1191 int r, fail = 0; 1192 u_char type; 1193 1194 if ((b = sshbuf_from(data, datalen)) == NULL) 1195 fatal_f("sshbuf_new"); 1196 if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0) 1197 fatal_fr(r, "parse sessionid"); 1198 1199 if ((session_id2 == NULL) || 1200 (len != session_id2_len) || 1201 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) 1202 fail++; 1203 1204 if ((r = sshbuf_get_u8(b, &type)) != 0) 1205 fatal_fr(r, "parse type"); 1206 if (type != SSH2_MSG_USERAUTH_REQUEST) 1207 fail++; 1208 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1209 fatal_fr(r, "parse userstyle"); 1210 xasprintf(&userstyle, "%s%s%s", authctxt->user, 1211 authctxt->style ? ":" : "", 1212 authctxt->style ? authctxt->style : ""); 1213 if (strcmp(userstyle, cp) != 0) { 1214 logit("wrong user name passed to monitor: " 1215 "expected %s != %.100s", userstyle, cp); 1216 fail++; 1217 } 1218 free(userstyle); 1219 free(cp); 1220 if ((r = sshbuf_skip_string(b)) != 0 || /* service */ 1221 (r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1222 fatal_fr(r, "parse method"); 1223 if (strcmp(cp, "hostbased") != 0) 1224 fail++; 1225 free(cp); 1226 if ((r = sshbuf_skip_string(b)) != 0 || /* pkalg */ 1227 (r = sshbuf_skip_string(b)) != 0) /* pkblob */ 1228 fatal_fr(r, "parse pk"); 1229 1230 /* verify client host, strip trailing dot if necessary */ 1231 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1232 fatal_fr(r, "parse host"); 1233 if (((len = strlen(cp)) > 0) && cp[len - 1] == '.') 1234 cp[len - 1] = '\0'; 1235 if (strcmp(cp, chost) != 0) 1236 fail++; 1237 free(cp); 1238 1239 /* verify client user */ 1240 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1241 fatal_fr(r, "parse ruser"); 1242 if (strcmp(cp, cuser) != 0) 1243 fail++; 1244 free(cp); 1245 1246 if (sshbuf_len(b) != 0) 1247 fail++; 1248 sshbuf_free(b); 1249 return (fail == 0); 1250 } 1251 1252 int 1253 mm_answer_keyverify(struct ssh *ssh, int sock, struct sshbuf *m) 1254 { 1255 struct sshkey *key; 1256 const u_char *signature, *data, *blob; 1257 char *sigalg = NULL, *fp = NULL; 1258 size_t signaturelen, datalen, bloblen; 1259 int r, ret, req_presence = 0, req_verify = 0, valid_data = 0; 1260 int encoded_ret; 1261 struct sshkey_sig_details *sig_details = NULL; 1262 1263 if ((r = sshbuf_get_string_direct(m, &blob, &bloblen)) != 0 || 1264 (r = sshbuf_get_string_direct(m, &signature, &signaturelen)) != 0 || 1265 (r = sshbuf_get_string_direct(m, &data, &datalen)) != 0 || 1266 (r = sshbuf_get_cstring(m, &sigalg, NULL)) != 0) 1267 fatal_fr(r, "parse"); 1268 1269 if (hostbased_cuser == NULL || hostbased_chost == NULL || 1270 !monitor_allowed_key(blob, bloblen)) 1271 fatal_f("bad key, not previously allowed"); 1272 1273 /* Empty signature algorithm means NULL. */ 1274 if (*sigalg == '\0') { 1275 free(sigalg); 1276 sigalg = NULL; 1277 } 1278 1279 /* XXX use sshkey_froms here; need to change key_blob, etc. */ 1280 if ((r = sshkey_from_blob(blob, bloblen, &key)) != 0) 1281 fatal_fr(r, "parse key"); 1282 1283 switch (key_blobtype) { 1284 case MM_USERKEY: 1285 valid_data = monitor_valid_userblob(ssh, data, datalen); 1286 auth_method = "publickey"; 1287 break; 1288 case MM_HOSTKEY: 1289 valid_data = monitor_valid_hostbasedblob(data, datalen, 1290 hostbased_cuser, hostbased_chost); 1291 auth_method = "hostbased"; 1292 break; 1293 default: 1294 valid_data = 0; 1295 break; 1296 } 1297 if (!valid_data) 1298 fatal_f("bad %s signature data blob", 1299 key_blobtype == MM_USERKEY ? "userkey" : 1300 (key_blobtype == MM_HOSTKEY ? "hostkey" : "unknown")); 1301 1302 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, 1303 SSH_FP_DEFAULT)) == NULL) 1304 fatal_f("sshkey_fingerprint failed"); 1305 1306 ret = sshkey_verify(key, signature, signaturelen, data, datalen, 1307 sigalg, ssh->compat, &sig_details); 1308 debug3_f("%s %s signature using %s %s%s%s", auth_method, 1309 sshkey_type(key), sigalg == NULL ? "default" : sigalg, 1310 (ret == 0) ? "verified" : "unverified", 1311 (ret != 0) ? ": " : "", (ret != 0) ? ssh_err(ret) : ""); 1312 1313 if (ret == 0 && key_blobtype == MM_USERKEY && sig_details != NULL) { 1314 req_presence = (options.pubkey_auth_options & 1315 PUBKEYAUTH_TOUCH_REQUIRED) || 1316 !key_opts->no_require_user_presence; 1317 if (req_presence && 1318 (sig_details->sk_flags & SSH_SK_USER_PRESENCE_REQD) == 0) { 1319 error("public key %s %s signature for %s%s from %.128s " 1320 "port %d rejected: user presence " 1321 "(authenticator touch) requirement not met ", 1322 sshkey_type(key), fp, 1323 authctxt->valid ? "" : "invalid user ", 1324 authctxt->user, ssh_remote_ipaddr(ssh), 1325 ssh_remote_port(ssh)); 1326 ret = SSH_ERR_SIGNATURE_INVALID; 1327 } 1328 req_verify = (options.pubkey_auth_options & 1329 PUBKEYAUTH_VERIFY_REQUIRED) || key_opts->require_verify; 1330 if (req_verify && 1331 (sig_details->sk_flags & SSH_SK_USER_VERIFICATION_REQD) == 0) { 1332 error("public key %s %s signature for %s%s from %.128s " 1333 "port %d rejected: user verification requirement " 1334 "not met ", sshkey_type(key), fp, 1335 authctxt->valid ? "" : "invalid user ", 1336 authctxt->user, ssh_remote_ipaddr(ssh), 1337 ssh_remote_port(ssh)); 1338 ret = SSH_ERR_SIGNATURE_INVALID; 1339 } 1340 } 1341 auth2_record_key(authctxt, ret == 0, key); 1342 1343 if (key_blobtype == MM_USERKEY && ret == 0) 1344 auth_activate_options(ssh, key_opts); 1345 monitor_reset_key_state(); 1346 1347 sshbuf_reset(m); 1348 1349 /* encode ret != 0 as positive integer, since we're sending u32 */ 1350 encoded_ret = (ret != 0); 1351 if ((r = sshbuf_put_u32(m, encoded_ret)) != 0 || 1352 (r = sshbuf_put_u8(m, sig_details != NULL)) != 0) 1353 fatal_fr(r, "assemble"); 1354 if (sig_details != NULL) { 1355 if ((r = sshbuf_put_u32(m, sig_details->sk_counter)) != 0 || 1356 (r = sshbuf_put_u8(m, sig_details->sk_flags)) != 0) 1357 fatal_fr(r, "assemble sk"); 1358 } 1359 sshkey_sig_details_free(sig_details); 1360 mm_request_send(sock, MONITOR_ANS_KEYVERIFY, m); 1361 1362 free(sigalg); 1363 free(fp); 1364 sshkey_free(key); 1365 1366 return ret == 0; 1367 } 1368 1369 static void 1370 mm_record_login(struct ssh *ssh, Session *s, struct passwd *pw) 1371 { 1372 socklen_t fromlen; 1373 struct sockaddr_storage from; 1374 1375 /* 1376 * Get IP address of client. If the connection is not a socket, let 1377 * the address be 0.0.0.0. 1378 */ 1379 memset(&from, 0, sizeof(from)); 1380 fromlen = sizeof(from); 1381 if (ssh_packet_connection_is_on_socket(ssh)) { 1382 if (getpeername(ssh_packet_get_connection_in(ssh), 1383 (struct sockaddr *)&from, &fromlen) == -1) { 1384 debug("getpeername: %.100s", strerror(errno)); 1385 cleanup_exit(255); 1386 } 1387 } 1388 /* Record that there was a login on that tty from the remote host. */ 1389 record_login(s->pid, s->tty, pw->pw_name, pw->pw_uid, 1390 session_get_remote_name_or_ip(ssh, utmp_len, options.use_dns), 1391 (struct sockaddr *)&from, fromlen); 1392 } 1393 1394 static void 1395 mm_session_close(Session *s) 1396 { 1397 debug3_f("session %d pid %ld", s->self, (long)s->pid); 1398 if (s->ttyfd != -1) { 1399 debug3_f("tty %s ptyfd %d", s->tty, s->ptyfd); 1400 session_pty_cleanup2(s); 1401 } 1402 session_unused(s->self); 1403 } 1404 1405 int 1406 mm_answer_pty(struct ssh *ssh, int sock, struct sshbuf *m) 1407 { 1408 extern struct monitor *pmonitor; 1409 Session *s; 1410 int r, res, fd0; 1411 1412 debug3_f("entering"); 1413 1414 sshbuf_reset(m); 1415 s = session_new(); 1416 if (s == NULL) 1417 goto error; 1418 s->authctxt = authctxt; 1419 s->pw = authctxt->pw; 1420 s->pid = pmonitor->m_pid; 1421 res = pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty)); 1422 if (res == 0) 1423 goto error; 1424 pty_setowner(authctxt->pw, s->tty); 1425 1426 if ((r = sshbuf_put_u32(m, 1)) != 0 || 1427 (r = sshbuf_put_cstring(m, s->tty)) != 0) 1428 fatal_fr(r, "assemble"); 1429 1430 /* We need to trick ttyslot */ 1431 if (dup2(s->ttyfd, 0) == -1) 1432 fatal_f("dup2"); 1433 1434 mm_record_login(ssh, s, authctxt->pw); 1435 1436 /* Now we can close the file descriptor again */ 1437 close(0); 1438 1439 /* send messages generated by record_login */ 1440 if ((r = sshbuf_put_stringb(m, loginmsg)) != 0) 1441 fatal_fr(r, "assemble loginmsg"); 1442 sshbuf_reset(loginmsg); 1443 1444 mm_request_send(sock, MONITOR_ANS_PTY, m); 1445 1446 if (mm_send_fd(sock, s->ptyfd) == -1 || 1447 mm_send_fd(sock, s->ttyfd) == -1) 1448 fatal_f("send fds failed"); 1449 1450 /* make sure nothing uses fd 0 */ 1451 if ((fd0 = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1452 fatal_f("open(/dev/null): %s", strerror(errno)); 1453 if (fd0 != 0) 1454 error_f("fd0 %d != 0", fd0); 1455 1456 /* slave side of pty is not needed */ 1457 close(s->ttyfd); 1458 s->ttyfd = s->ptyfd; 1459 /* no need to dup() because nobody closes ptyfd */ 1460 s->ptymaster = s->ptyfd; 1461 1462 debug3_f("tty %s ptyfd %d", s->tty, s->ttyfd); 1463 1464 return (0); 1465 1466 error: 1467 if (s != NULL) 1468 mm_session_close(s); 1469 if ((r = sshbuf_put_u32(m, 0)) != 0) 1470 fatal_fr(r, "assemble 0"); 1471 mm_request_send(sock, MONITOR_ANS_PTY, m); 1472 return (0); 1473 } 1474 1475 int 1476 mm_answer_pty_cleanup(struct ssh *ssh, int sock, struct sshbuf *m) 1477 { 1478 Session *s; 1479 char *tty; 1480 int r; 1481 1482 debug3_f("entering"); 1483 1484 if ((r = sshbuf_get_cstring(m, &tty, NULL)) != 0) 1485 fatal_fr(r, "parse tty"); 1486 if ((s = session_by_tty(tty)) != NULL) 1487 mm_session_close(s); 1488 sshbuf_reset(m); 1489 free(tty); 1490 return (0); 1491 } 1492 1493 int 1494 mm_answer_term(struct ssh *ssh, int sock, struct sshbuf *req) 1495 { 1496 extern struct monitor *pmonitor; 1497 int res, status; 1498 1499 debug3_f("tearing down sessions"); 1500 1501 /* The child is terminating */ 1502 session_destroy_all(ssh, &mm_session_close); 1503 1504 while (waitpid(pmonitor->m_pid, &status, 0) == -1) 1505 if (errno != EINTR) 1506 exit(1); 1507 1508 res = WIFEXITED(status) ? WEXITSTATUS(status) : 1; 1509 1510 /* Terminate process */ 1511 exit(res); 1512 } 1513 1514 void 1515 monitor_clear_keystate(struct ssh *ssh, struct monitor *pmonitor) 1516 { 1517 ssh_clear_newkeys(ssh, MODE_IN); 1518 ssh_clear_newkeys(ssh, MODE_OUT); 1519 sshbuf_free(child_state); 1520 child_state = NULL; 1521 } 1522 1523 void 1524 monitor_apply_keystate(struct ssh *ssh, struct monitor *pmonitor) 1525 { 1526 struct kex *kex; 1527 int r; 1528 1529 debug3_f("packet_set_state"); 1530 if ((r = ssh_packet_set_state(ssh, child_state)) != 0) 1531 fatal_fr(r, "packet_set_state"); 1532 sshbuf_free(child_state); 1533 child_state = NULL; 1534 if ((kex = ssh->kex) == NULL) 1535 fatal_f("internal error: ssh->kex == NULL"); 1536 if (session_id2_len != sshbuf_len(ssh->kex->session_id)) { 1537 fatal_f("incorrect session id length %zu (expected %u)", 1538 sshbuf_len(ssh->kex->session_id), session_id2_len); 1539 } 1540 if (memcmp(sshbuf_ptr(ssh->kex->session_id), session_id2, 1541 session_id2_len) != 0) 1542 fatal_f("session ID mismatch"); 1543 /* XXX set callbacks */ 1544 #ifdef WITH_OPENSSL 1545 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server; 1546 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server; 1547 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server; 1548 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server; 1549 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server; 1550 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 1551 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 1552 kex->kex[KEX_ECDH_SHA2] = kex_gen_server; 1553 #endif 1554 kex->kex[KEX_C25519_SHA256] = kex_gen_server; 1555 kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server; 1556 kex->kex[KEX_KEM_MLKEM768X25519_SHA256] = kex_gen_server; 1557 kex->load_host_public_key=&get_hostkey_public_by_type; 1558 kex->load_host_private_key=&get_hostkey_private_by_type; 1559 kex->host_key_index=&get_hostkey_index; 1560 kex->sign = sshd_hostkey_sign; 1561 } 1562 1563 /* This function requires careful sanity checking */ 1564 1565 void 1566 mm_get_keystate(struct ssh *ssh, struct monitor *pmonitor) 1567 { 1568 debug3_f("Waiting for new keys"); 1569 1570 if ((child_state = sshbuf_new()) == NULL) 1571 fatal_f("sshbuf_new failed"); 1572 mm_request_receive_expect(pmonitor->m_sendfd, MONITOR_REQ_KEYEXPORT, 1573 child_state); 1574 debug3_f("GOT new keys"); 1575 } 1576 1577 1578 /* XXX */ 1579 1580 #define FD_CLOSEONEXEC(x) do { \ 1581 if (fcntl(x, F_SETFD, FD_CLOEXEC) == -1) \ 1582 fatal("fcntl(%d, F_SETFD)", x); \ 1583 } while (0) 1584 1585 static void 1586 monitor_openfds(struct monitor *mon, int do_logfds) 1587 { 1588 int pair[2]; 1589 #ifdef SO_ZEROIZE 1590 int on = 1; 1591 #endif 1592 1593 if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) 1594 fatal_f("socketpair: %s", strerror(errno)); 1595 #ifdef SO_ZEROIZE 1596 if (setsockopt(pair[0], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1) 1597 error("setsockopt SO_ZEROIZE(0): %.100s", strerror(errno)); 1598 if (setsockopt(pair[1], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1) 1599 error("setsockopt SO_ZEROIZE(1): %.100s", strerror(errno)); 1600 #endif 1601 FD_CLOSEONEXEC(pair[0]); 1602 FD_CLOSEONEXEC(pair[1]); 1603 mon->m_recvfd = pair[0]; 1604 mon->m_sendfd = pair[1]; 1605 1606 if (do_logfds) { 1607 if (pipe(pair) == -1) 1608 fatal_f("pipe: %s", strerror(errno)); 1609 FD_CLOSEONEXEC(pair[0]); 1610 FD_CLOSEONEXEC(pair[1]); 1611 mon->m_log_recvfd = pair[0]; 1612 mon->m_log_sendfd = pair[1]; 1613 } else 1614 mon->m_log_recvfd = mon->m_log_sendfd = -1; 1615 } 1616 1617 struct monitor * 1618 monitor_init(void) 1619 { 1620 struct monitor *mon; 1621 1622 mon = xcalloc(1, sizeof(*mon)); 1623 monitor_openfds(mon, 1); 1624 1625 return mon; 1626 } 1627 1628 void 1629 monitor_reinit(struct monitor *mon) 1630 { 1631 monitor_openfds(mon, 0); 1632 } 1633 1634 #ifdef GSSAPI 1635 int 1636 mm_answer_gss_setup_ctx(struct ssh *ssh, int sock, struct sshbuf *m) 1637 { 1638 gss_OID_desc goid; 1639 OM_uint32 major; 1640 size_t len; 1641 u_char *p; 1642 int r; 1643 1644 if (!options.gss_authentication) 1645 fatal_f("GSSAPI authentication not enabled"); 1646 1647 if ((r = sshbuf_get_string(m, &p, &len)) != 0) 1648 fatal_fr(r, "parse"); 1649 goid.elements = p; 1650 goid.length = len; 1651 1652 major = ssh_gssapi_server_ctx(&gsscontext, &goid); 1653 1654 free(goid.elements); 1655 1656 sshbuf_reset(m); 1657 if ((r = sshbuf_put_u32(m, major)) != 0) 1658 fatal_fr(r, "assemble"); 1659 1660 mm_request_send(sock, MONITOR_ANS_GSSSETUP, m); 1661 1662 /* Now we have a context, enable the step */ 1663 monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 1); 1664 1665 return (0); 1666 } 1667 1668 int 1669 mm_answer_gss_accept_ctx(struct ssh *ssh, int sock, struct sshbuf *m) 1670 { 1671 gss_buffer_desc in; 1672 gss_buffer_desc out = GSS_C_EMPTY_BUFFER; 1673 OM_uint32 major, minor; 1674 OM_uint32 flags = 0; /* GSI needs this */ 1675 int r; 1676 1677 if (!options.gss_authentication) 1678 fatal_f("GSSAPI authentication not enabled"); 1679 1680 if ((r = ssh_gssapi_get_buffer_desc(m, &in)) != 0) 1681 fatal_fr(r, "ssh_gssapi_get_buffer_desc"); 1682 major = ssh_gssapi_accept_ctx(gsscontext, &in, &out, &flags); 1683 free(in.value); 1684 1685 sshbuf_reset(m); 1686 if ((r = sshbuf_put_u32(m, major)) != 0 || 1687 (r = sshbuf_put_string(m, out.value, out.length)) != 0 || 1688 (r = sshbuf_put_u32(m, flags)) != 0) 1689 fatal_fr(r, "assemble"); 1690 mm_request_send(sock, MONITOR_ANS_GSSSTEP, m); 1691 1692 gss_release_buffer(&minor, &out); 1693 1694 if (major == GSS_S_COMPLETE) { 1695 monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 0); 1696 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1); 1697 monitor_permit(mon_dispatch, MONITOR_REQ_GSSCHECKMIC, 1); 1698 } 1699 return (0); 1700 } 1701 1702 int 1703 mm_answer_gss_checkmic(struct ssh *ssh, int sock, struct sshbuf *m) 1704 { 1705 gss_buffer_desc gssbuf, mic; 1706 OM_uint32 ret; 1707 int r; 1708 1709 if (!options.gss_authentication) 1710 fatal_f("GSSAPI authentication not enabled"); 1711 1712 if ((r = ssh_gssapi_get_buffer_desc(m, &gssbuf)) != 0 || 1713 (r = ssh_gssapi_get_buffer_desc(m, &mic)) != 0) 1714 fatal_fr(r, "ssh_gssapi_get_buffer_desc"); 1715 1716 ret = ssh_gssapi_checkmic(gsscontext, &gssbuf, &mic); 1717 1718 free(gssbuf.value); 1719 free(mic.value); 1720 1721 sshbuf_reset(m); 1722 if ((r = sshbuf_put_u32(m, ret)) != 0) 1723 fatal_fr(r, "assemble"); 1724 1725 mm_request_send(sock, MONITOR_ANS_GSSCHECKMIC, m); 1726 1727 if (!GSS_ERROR(ret)) 1728 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1); 1729 1730 return (0); 1731 } 1732 1733 int 1734 mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m) 1735 { 1736 int r, authenticated; 1737 const char *displayname; 1738 1739 if (!options.gss_authentication) 1740 fatal_f("GSSAPI authentication not enabled"); 1741 1742 authenticated = authctxt->valid && ssh_gssapi_userok(authctxt->user); 1743 1744 sshbuf_reset(m); 1745 if ((r = sshbuf_put_u32(m, authenticated)) != 0) 1746 fatal_fr(r, "assemble"); 1747 1748 debug3_f("sending result %d", authenticated); 1749 mm_request_send(sock, MONITOR_ANS_GSSUSEROK, m); 1750 1751 auth_method = "gssapi-with-mic"; 1752 1753 if ((displayname = ssh_gssapi_displayname()) != NULL) 1754 auth2_record_info(authctxt, "%s", displayname); 1755 1756 /* Monitor loop will terminate if authenticated */ 1757 return (authenticated); 1758 } 1759 #endif /* GSSAPI */ 1760 1761