1 /* $OpenBSD: monitor.c,v 1.225 2021/04/15 16:24:31 markus 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_skeyquery(struct ssh *, int, struct sshbuf *); 109 int mm_answer_skeyrespond(struct ssh *, int, struct sshbuf *); 110 int mm_answer_keyallowed(struct ssh *, int, struct sshbuf *); 111 int mm_answer_keyverify(struct ssh *, int, struct sshbuf *); 112 int mm_answer_pty(struct ssh *, int, struct sshbuf *); 113 int mm_answer_pty_cleanup(struct ssh *, int, struct sshbuf *); 114 int mm_answer_term(struct ssh *, int, struct sshbuf *); 115 int mm_answer_rsa_keyallowed(struct ssh *, int, struct sshbuf *); 116 int mm_answer_rsa_challenge(struct ssh *, int, struct sshbuf *); 117 int mm_answer_rsa_response(struct ssh *, int, struct sshbuf *); 118 int mm_answer_sesskey(struct ssh *, int, struct sshbuf *); 119 int mm_answer_sessid(struct ssh *, int, struct sshbuf *); 120 121 #ifdef GSSAPI 122 int mm_answer_gss_setup_ctx(struct ssh *, int, struct sshbuf *); 123 int mm_answer_gss_accept_ctx(struct ssh *, int, struct sshbuf *); 124 int mm_answer_gss_userok(struct ssh *, int, struct sshbuf *); 125 int mm_answer_gss_checkmic(struct ssh *, int, struct sshbuf *); 126 #endif 127 128 static Authctxt *authctxt; 129 130 /* local state for key verify */ 131 static u_char *key_blob = NULL; 132 static size_t key_bloblen = 0; 133 static u_int key_blobtype = MM_NOKEY; 134 static struct sshauthopt *key_opts = NULL; 135 static char *hostbased_cuser = NULL; 136 static char *hostbased_chost = NULL; 137 static char *auth_method = "unknown"; 138 static char *auth_submethod = NULL; 139 static u_int session_id2_len = 0; 140 static u_char *session_id2 = NULL; 141 static pid_t monitor_child_pid; 142 143 struct mon_table { 144 enum monitor_reqtype type; 145 int flags; 146 int (*f)(struct ssh *, int, struct sshbuf *); 147 }; 148 149 #define MON_ISAUTH 0x0004 /* Required for Authentication */ 150 #define MON_AUTHDECIDE 0x0008 /* Decides Authentication */ 151 #define MON_ONCE 0x0010 /* Disable after calling */ 152 #define MON_ALOG 0x0020 /* Log auth attempt without authenticating */ 153 154 #define MON_AUTH (MON_ISAUTH|MON_AUTHDECIDE) 155 156 #define MON_PERMIT 0x1000 /* Request is permitted */ 157 158 static int monitor_read(struct ssh *, struct monitor *, struct mon_table *, 159 struct mon_table **); 160 static int monitor_read_log(struct monitor *); 161 162 struct mon_table mon_dispatch_proto20[] = { 163 #ifdef WITH_OPENSSL 164 {MONITOR_REQ_MODULI, MON_ONCE, mm_answer_moduli}, 165 #endif 166 {MONITOR_REQ_SIGN, MON_ONCE, mm_answer_sign}, 167 {MONITOR_REQ_PWNAM, MON_ONCE, mm_answer_pwnamallow}, 168 {MONITOR_REQ_AUTHSERV, MON_ONCE, mm_answer_authserv}, 169 {MONITOR_REQ_AUTH2_READ_BANNER, MON_ONCE, mm_answer_auth2_read_banner}, 170 {MONITOR_REQ_AUTHPASSWORD, MON_AUTH, mm_answer_authpassword}, 171 {MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery}, 172 {MONITOR_REQ_BSDAUTHRESPOND, MON_AUTH, mm_answer_bsdauthrespond}, 173 {MONITOR_REQ_KEYALLOWED, MON_ISAUTH, mm_answer_keyallowed}, 174 {MONITOR_REQ_KEYVERIFY, MON_AUTH, mm_answer_keyverify}, 175 #ifdef GSSAPI 176 {MONITOR_REQ_GSSSETUP, MON_ISAUTH, mm_answer_gss_setup_ctx}, 177 {MONITOR_REQ_GSSSTEP, 0, mm_answer_gss_accept_ctx}, 178 {MONITOR_REQ_GSSUSEROK, MON_ONCE|MON_AUTHDECIDE, mm_answer_gss_userok}, 179 {MONITOR_REQ_GSSCHECKMIC, MON_ONCE, mm_answer_gss_checkmic}, 180 #endif 181 {0, 0, NULL} 182 }; 183 184 struct mon_table mon_dispatch_postauth20[] = { 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 moduli and signatures */ 245 monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); 246 monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); 247 248 /* The first few requests do not require asynchronous access */ 249 while (!authenticated) { 250 partial = 0; 251 auth_method = "unknown"; 252 auth_submethod = NULL; 253 auth2_authctxt_reset_info(authctxt); 254 255 authenticated = (monitor_read(ssh, pmonitor, 256 mon_dispatch, &ent) == 1); 257 258 /* Special handling for multiple required authentications */ 259 if (options.num_auth_methods != 0) { 260 if (authenticated && 261 !auth2_update_methods_lists(authctxt, 262 auth_method, auth_submethod)) { 263 debug3_f("method %s: partial", auth_method); 264 authenticated = 0; 265 partial = 1; 266 } 267 } 268 269 if (authenticated) { 270 if (!(ent->flags & MON_AUTHDECIDE)) 271 fatal_f("unexpected authentication from %d", 272 ent->type); 273 if (authctxt->pw->pw_uid == 0 && 274 !auth_root_allowed(ssh, auth_method)) 275 authenticated = 0; 276 } 277 if (ent->flags & (MON_AUTHDECIDE|MON_ALOG)) { 278 auth_log(ssh, authenticated, partial, 279 auth_method, auth_submethod); 280 if (!partial && !authenticated) 281 authctxt->failures++; 282 if (authenticated || partial) { 283 auth2_update_session_info(authctxt, 284 auth_method, auth_submethod); 285 } 286 } 287 } 288 289 if (!authctxt->valid) 290 fatal_f("authenticated invalid user"); 291 if (strcmp(auth_method, "unknown") == 0) 292 fatal_f("authentication method name unknown"); 293 294 debug_f("user %s authenticated by privileged process", authctxt->user); 295 ssh->authctxt = NULL; 296 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 297 298 mm_get_keystate(ssh, pmonitor); 299 300 /* Drain any buffered messages from the child */ 301 while (pmonitor->m_log_recvfd != -1 && monitor_read_log(pmonitor) == 0) 302 ; 303 304 if (pmonitor->m_recvfd >= 0) 305 close(pmonitor->m_recvfd); 306 if (pmonitor->m_log_sendfd >= 0) 307 close(pmonitor->m_log_sendfd); 308 pmonitor->m_sendfd = pmonitor->m_log_recvfd = -1; 309 } 310 311 static void 312 monitor_set_child_handler(pid_t pid) 313 { 314 monitor_child_pid = pid; 315 } 316 317 static void 318 monitor_child_handler(int sig) 319 { 320 kill(monitor_child_pid, sig); 321 } 322 323 void 324 monitor_child_postauth(struct ssh *ssh, struct monitor *pmonitor) 325 { 326 close(pmonitor->m_recvfd); 327 pmonitor->m_recvfd = -1; 328 329 monitor_set_child_handler(pmonitor->m_pid); 330 ssh_signal(SIGHUP, &monitor_child_handler); 331 ssh_signal(SIGTERM, &monitor_child_handler); 332 ssh_signal(SIGINT, &monitor_child_handler); 333 334 mon_dispatch = mon_dispatch_postauth20; 335 336 /* Permit requests for moduli and signatures */ 337 monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); 338 monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); 339 monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1); 340 341 if (auth_opts->permit_pty_flag) { 342 monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1); 343 monitor_permit(mon_dispatch, MONITOR_REQ_PTYCLEANUP, 1); 344 } 345 346 for (;;) 347 monitor_read(ssh, pmonitor, mon_dispatch, NULL); 348 } 349 350 static int 351 monitor_read_log(struct monitor *pmonitor) 352 { 353 struct sshbuf *logmsg; 354 u_int len, level, forced; 355 char *msg; 356 u_char *p; 357 int r; 358 359 if ((logmsg = sshbuf_new()) == NULL) 360 fatal_f("sshbuf_new"); 361 362 /* Read length */ 363 if ((r = sshbuf_reserve(logmsg, 4, &p)) != 0) 364 fatal_fr(r, "reserve len"); 365 if (atomicio(read, pmonitor->m_log_recvfd, p, 4) != 4) { 366 if (errno == EPIPE) { 367 sshbuf_free(logmsg); 368 debug_f("child log fd closed"); 369 close(pmonitor->m_log_recvfd); 370 pmonitor->m_log_recvfd = -1; 371 return -1; 372 } 373 fatal_f("log fd read: %s", strerror(errno)); 374 } 375 if ((r = sshbuf_get_u32(logmsg, &len)) != 0) 376 fatal_fr(r, "parse len"); 377 if (len <= 4 || len > 8192) 378 fatal_f("invalid log message length %u", len); 379 380 /* Read severity, message */ 381 sshbuf_reset(logmsg); 382 if ((r = sshbuf_reserve(logmsg, len, &p)) != 0) 383 fatal_fr(r, "reserve msg"); 384 if (atomicio(read, pmonitor->m_log_recvfd, p, len) != len) 385 fatal_f("log fd read: %s", strerror(errno)); 386 if ((r = sshbuf_get_u32(logmsg, &level)) != 0 || 387 (r = sshbuf_get_u32(logmsg, &forced)) != 0 || 388 (r = sshbuf_get_cstring(logmsg, &msg, NULL)) != 0) 389 fatal_fr(r, "parse"); 390 391 /* Log it */ 392 if (log_level_name(level) == NULL) 393 fatal_f("invalid log level %u (corrupted message?)", level); 394 sshlogdirect(level, forced, "%s [preauth]", msg); 395 396 sshbuf_free(logmsg); 397 free(msg); 398 399 return 0; 400 } 401 402 static int 403 monitor_read(struct ssh *ssh, struct monitor *pmonitor, struct mon_table *ent, 404 struct mon_table **pent) 405 { 406 struct sshbuf *m; 407 int r, ret; 408 u_char type; 409 struct pollfd pfd[2]; 410 411 for (;;) { 412 memset(&pfd, 0, sizeof(pfd)); 413 pfd[0].fd = pmonitor->m_sendfd; 414 pfd[0].events = POLLIN; 415 pfd[1].fd = pmonitor->m_log_recvfd; 416 pfd[1].events = pfd[1].fd == -1 ? 0 : POLLIN; 417 if (poll(pfd, pfd[1].fd == -1 ? 1 : 2, -1) == -1) { 418 if (errno == EINTR || errno == EAGAIN) 419 continue; 420 fatal_f("poll: %s", strerror(errno)); 421 } 422 if (pfd[1].revents) { 423 /* 424 * Drain all log messages before processing next 425 * monitor request. 426 */ 427 monitor_read_log(pmonitor); 428 continue; 429 } 430 if (pfd[0].revents) 431 break; /* Continues below */ 432 } 433 434 if ((m = sshbuf_new()) == NULL) 435 fatal_f("sshbuf_new"); 436 437 mm_request_receive(pmonitor->m_sendfd, m); 438 if ((r = sshbuf_get_u8(m, &type)) != 0) 439 fatal_fr(r, "parse type"); 440 441 debug3_f("checking request %d", type); 442 443 while (ent->f != NULL) { 444 if (ent->type == type) 445 break; 446 ent++; 447 } 448 449 if (ent->f != NULL) { 450 if (!(ent->flags & MON_PERMIT)) 451 fatal_f("unpermitted request %d", type); 452 ret = (*ent->f)(ssh, pmonitor->m_sendfd, m); 453 sshbuf_free(m); 454 455 /* The child may use this request only once, disable it */ 456 if (ent->flags & MON_ONCE) { 457 debug2_f("%d used once, disabling now", type); 458 ent->flags &= ~MON_PERMIT; 459 } 460 461 if (pent != NULL) 462 *pent = ent; 463 464 return ret; 465 } 466 467 fatal_f("unsupported request: %d", type); 468 469 /* NOTREACHED */ 470 return (-1); 471 } 472 473 /* allowed key state */ 474 static int 475 monitor_allowed_key(const u_char *blob, u_int bloblen) 476 { 477 /* make sure key is allowed */ 478 if (key_blob == NULL || key_bloblen != bloblen || 479 timingsafe_bcmp(key_blob, blob, key_bloblen)) 480 return (0); 481 return (1); 482 } 483 484 static void 485 monitor_reset_key_state(void) 486 { 487 /* reset state */ 488 free(key_blob); 489 free(hostbased_cuser); 490 free(hostbased_chost); 491 sshauthopt_free(key_opts); 492 key_blob = NULL; 493 key_bloblen = 0; 494 key_blobtype = MM_NOKEY; 495 key_opts = NULL; 496 hostbased_cuser = NULL; 497 hostbased_chost = NULL; 498 } 499 500 #ifdef WITH_OPENSSL 501 int 502 mm_answer_moduli(struct ssh *ssh, int sock, struct sshbuf *m) 503 { 504 DH *dh; 505 const BIGNUM *dh_p, *dh_g; 506 int r; 507 u_int min, want, max; 508 509 if ((r = sshbuf_get_u32(m, &min)) != 0 || 510 (r = sshbuf_get_u32(m, &want)) != 0 || 511 (r = sshbuf_get_u32(m, &max)) != 0) 512 fatal_fr(r, "parse"); 513 514 debug3_f("got parameters: %d %d %d", min, want, max); 515 /* We need to check here, too, in case the child got corrupted */ 516 if (max < min || want < min || max < want) 517 fatal_f("bad parameters: %d %d %d", min, want, max); 518 519 sshbuf_reset(m); 520 521 dh = choose_dh(min, want, max); 522 if (dh == NULL) { 523 if ((r = sshbuf_put_u8(m, 0)) != 0) 524 fatal_fr(r, "assemble empty"); 525 return (0); 526 } else { 527 /* Send first bignum */ 528 DH_get0_pqg(dh, &dh_p, NULL, &dh_g); 529 if ((r = sshbuf_put_u8(m, 1)) != 0 || 530 (r = sshbuf_put_bignum2(m, dh_p)) != 0 || 531 (r = sshbuf_put_bignum2(m, dh_g)) != 0) 532 fatal_fr(r, "assemble"); 533 534 DH_free(dh); 535 } 536 mm_request_send(sock, MONITOR_ANS_MODULI, m); 537 return (0); 538 } 539 #endif 540 541 int 542 mm_answer_sign(struct ssh *ssh, int sock, struct sshbuf *m) 543 { 544 extern int auth_sock; /* XXX move to state struct? */ 545 struct sshkey *key; 546 struct sshbuf *sigbuf = NULL; 547 u_char *p = NULL, *signature = NULL; 548 char *alg = NULL; 549 size_t datlen, siglen, alglen; 550 int r, is_proof = 0; 551 u_int keyid, compat; 552 const char proof_req[] = "hostkeys-prove-00@openssh.com"; 553 554 debug3_f("entering"); 555 556 if ((r = sshbuf_get_u32(m, &keyid)) != 0 || 557 (r = sshbuf_get_string(m, &p, &datlen)) != 0 || 558 (r = sshbuf_get_cstring(m, &alg, &alglen)) != 0 || 559 (r = sshbuf_get_u32(m, &compat)) != 0) 560 fatal_fr(r, "parse"); 561 if (keyid > INT_MAX) 562 fatal_f("invalid key ID"); 563 564 /* 565 * Supported KEX types use SHA1 (20 bytes), SHA256 (32 bytes), 566 * SHA384 (48 bytes) and SHA512 (64 bytes). 567 * 568 * Otherwise, verify the signature request is for a hostkey 569 * proof. 570 * 571 * XXX perform similar check for KEX signature requests too? 572 * it's not trivial, since what is signed is the hash, rather 573 * than the full kex structure... 574 */ 575 if (datlen != 20 && datlen != 32 && datlen != 48 && datlen != 64) { 576 /* 577 * Construct expected hostkey proof and compare it to what 578 * the client sent us. 579 */ 580 if (session_id2_len == 0) /* hostkeys is never first */ 581 fatal_f("bad data length: %zu", datlen); 582 if ((key = get_hostkey_public_by_index(keyid, ssh)) == NULL) 583 fatal_f("no hostkey for index %d", keyid); 584 if ((sigbuf = sshbuf_new()) == NULL) 585 fatal_f("sshbuf_new"); 586 if ((r = sshbuf_put_cstring(sigbuf, proof_req)) != 0 || 587 (r = sshbuf_put_string(sigbuf, session_id2, 588 session_id2_len)) != 0 || 589 (r = sshkey_puts(key, sigbuf)) != 0) 590 fatal_fr(r, "assemble private key proof"); 591 if (datlen != sshbuf_len(sigbuf) || 592 memcmp(p, sshbuf_ptr(sigbuf), sshbuf_len(sigbuf)) != 0) 593 fatal_f("bad data length: %zu, hostkey proof len %zu", 594 datlen, sshbuf_len(sigbuf)); 595 sshbuf_free(sigbuf); 596 is_proof = 1; 597 } 598 599 /* save session id, it will be passed on the first call */ 600 if (session_id2_len == 0) { 601 session_id2_len = datlen; 602 session_id2 = xmalloc(session_id2_len); 603 memcpy(session_id2, p, session_id2_len); 604 } 605 606 if ((key = get_hostkey_by_index(keyid)) != NULL) { 607 if ((r = sshkey_sign(key, &signature, &siglen, p, datlen, alg, 608 options.sk_provider, NULL, compat)) != 0) 609 fatal_fr(r, "sign"); 610 } else if ((key = get_hostkey_public_by_index(keyid, ssh)) != NULL && 611 auth_sock > 0) { 612 if ((r = ssh_agent_sign(auth_sock, key, &signature, &siglen, 613 p, datlen, alg, compat)) != 0) 614 fatal_fr(r, "agent sign"); 615 } else 616 fatal_f("no hostkey from index %d", keyid); 617 618 debug3_f("%s signature %p(%zu)", is_proof ? "hostkey proof" : "KEX", 619 signature, siglen); 620 621 sshbuf_reset(m); 622 if ((r = sshbuf_put_string(m, signature, siglen)) != 0) 623 fatal_fr(r, "assemble"); 624 625 free(alg); 626 free(p); 627 free(signature); 628 629 mm_request_send(sock, MONITOR_ANS_SIGN, m); 630 631 /* Turn on permissions for getpwnam */ 632 monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1); 633 634 return (0); 635 } 636 637 #define PUTPW(b, id) \ 638 do { \ 639 if ((r = sshbuf_put_string(b, \ 640 &pwent->id, sizeof(pwent->id))) != 0) \ 641 fatal_fr(r, "assemble %s", #id); \ 642 } while (0) 643 644 /* Retrieves the password entry and also checks if the user is permitted */ 645 int 646 mm_answer_pwnamallow(struct ssh *ssh, int sock, struct sshbuf *m) 647 { 648 char *username; 649 struct passwd *pwent; 650 int r, allowed = 0; 651 u_int i; 652 653 debug3_f("entering"); 654 655 if (authctxt->attempt++ != 0) 656 fatal_f("multiple attempts for getpwnam"); 657 658 if ((r = sshbuf_get_cstring(m, &username, NULL)) != 0) 659 fatal_fr(r, "parse"); 660 661 pwent = getpwnamallow(ssh, username); 662 663 authctxt->user = xstrdup(username); 664 setproctitle("%s [priv]", pwent ? username : "unknown"); 665 free(username); 666 667 sshbuf_reset(m); 668 669 if (pwent == NULL) { 670 if ((r = sshbuf_put_u8(m, 0)) != 0) 671 fatal_fr(r, "assemble fakepw"); 672 authctxt->pw = fakepw(); 673 goto out; 674 } 675 676 allowed = 1; 677 authctxt->pw = pwent; 678 authctxt->valid = 1; 679 680 /* XXX send fake class/dir/shell, etc. */ 681 if ((r = sshbuf_put_u8(m, 1)) != 0) 682 fatal_fr(r, "assemble ok"); 683 PUTPW(m, pw_uid); 684 PUTPW(m, pw_gid); 685 PUTPW(m, pw_change); 686 PUTPW(m, pw_expire); 687 if ((r = sshbuf_put_cstring(m, pwent->pw_name)) != 0 || 688 (r = sshbuf_put_cstring(m, "*")) != 0 || 689 (r = sshbuf_put_cstring(m, pwent->pw_gecos)) != 0 || 690 (r = sshbuf_put_cstring(m, pwent->pw_class)) != 0 || 691 (r = sshbuf_put_cstring(m, pwent->pw_dir)) != 0 || 692 (r = sshbuf_put_cstring(m, pwent->pw_shell)) != 0) 693 fatal_fr(r, "assemble pw"); 694 695 out: 696 ssh_packet_set_log_preamble(ssh, "%suser %s", 697 authctxt->valid ? "authenticating" : "invalid ", authctxt->user); 698 if ((r = sshbuf_put_string(m, &options, sizeof(options))) != 0) 699 fatal_fr(r, "assemble options"); 700 701 #define M_CP_STROPT(x) do { \ 702 if (options.x != NULL && \ 703 (r = sshbuf_put_cstring(m, options.x)) != 0) \ 704 fatal_fr(r, "assemble %s", #x); \ 705 } while (0) 706 #define M_CP_STRARRAYOPT(x, nx) do { \ 707 for (i = 0; i < options.nx; i++) { \ 708 if ((r = sshbuf_put_cstring(m, options.x[i])) != 0) \ 709 fatal_fr(r, "assemble %s", #x); \ 710 } \ 711 } while (0) 712 /* See comment in servconf.h */ 713 COPY_MATCH_STRING_OPTS(); 714 #undef M_CP_STROPT 715 #undef M_CP_STRARRAYOPT 716 717 /* Create valid auth method lists */ 718 if (auth2_setup_methods_lists(authctxt) != 0) { 719 /* 720 * The monitor will continue long enough to let the child 721 * run to it's packet_disconnect(), but it must not allow any 722 * authentication to succeed. 723 */ 724 debug_f("no valid authentication method lists"); 725 } 726 727 debug3_f("sending MONITOR_ANS_PWNAM: %d", allowed); 728 mm_request_send(sock, MONITOR_ANS_PWNAM, m); 729 730 /* Allow service/style information on the auth context */ 731 monitor_permit(mon_dispatch, MONITOR_REQ_AUTHSERV, 1); 732 monitor_permit(mon_dispatch, MONITOR_REQ_AUTH2_READ_BANNER, 1); 733 734 return (0); 735 } 736 737 int mm_answer_auth2_read_banner(struct ssh *ssh, int sock, struct sshbuf *m) 738 { 739 char *banner; 740 int r; 741 742 sshbuf_reset(m); 743 banner = auth2_read_banner(); 744 if ((r = sshbuf_put_cstring(m, banner != NULL ? banner : "")) != 0) 745 fatal_fr(r, "assemble"); 746 mm_request_send(sock, MONITOR_ANS_AUTH2_READ_BANNER, m); 747 free(banner); 748 749 return (0); 750 } 751 752 int 753 mm_answer_authserv(struct ssh *ssh, int sock, struct sshbuf *m) 754 { 755 int r; 756 757 monitor_permit_authentications(1); 758 759 if ((r = sshbuf_get_cstring(m, &authctxt->service, NULL)) != 0 || 760 (r = sshbuf_get_cstring(m, &authctxt->style, NULL)) != 0) 761 fatal_fr(r, "parse"); 762 debug3_f("service=%s, style=%s", authctxt->service, authctxt->style); 763 764 if (strlen(authctxt->style) == 0) { 765 free(authctxt->style); 766 authctxt->style = NULL; 767 } 768 769 return (0); 770 } 771 772 int 773 mm_answer_authpassword(struct ssh *ssh, int sock, struct sshbuf *m) 774 { 775 static int call_count; 776 char *passwd; 777 int r, authenticated; 778 size_t plen; 779 780 if (!options.password_authentication) 781 fatal_f("password authentication not enabled"); 782 if ((r = sshbuf_get_cstring(m, &passwd, &plen)) != 0) 783 fatal_fr(r, "parse"); 784 /* Only authenticate if the context is valid */ 785 authenticated = options.password_authentication && 786 auth_password(ssh, passwd); 787 freezero(passwd, plen); 788 789 sshbuf_reset(m); 790 if ((r = sshbuf_put_u32(m, authenticated)) != 0) 791 fatal_fr(r, "assemble"); 792 793 debug3_f("sending result %d", authenticated); 794 mm_request_send(sock, MONITOR_ANS_AUTHPASSWORD, m); 795 796 call_count++; 797 if (plen == 0 && call_count == 1) 798 auth_method = "none"; 799 else 800 auth_method = "password"; 801 802 /* Causes monitor loop to terminate if authenticated */ 803 return (authenticated); 804 } 805 806 int 807 mm_answer_bsdauthquery(struct ssh *ssh, int sock, struct sshbuf *m) 808 { 809 char *name, *infotxt; 810 u_int numprompts, *echo_on, success; 811 char **prompts; 812 int r; 813 814 if (!options.kbd_interactive_authentication) 815 fatal_f("kbd-int authentication not enabled"); 816 success = bsdauth_query(authctxt, &name, &infotxt, &numprompts, 817 &prompts, &echo_on) < 0 ? 0 : 1; 818 819 sshbuf_reset(m); 820 if ((r = sshbuf_put_u32(m, success)) != 0) 821 fatal_fr(r, "assemble"); 822 if (success) { 823 if ((r = sshbuf_put_cstring(m, prompts[0])) != 0) 824 fatal_fr(r, "assemble prompt"); 825 } 826 827 debug3_f("sending challenge success: %u", success); 828 mm_request_send(sock, MONITOR_ANS_BSDAUTHQUERY, m); 829 830 if (success) { 831 free(name); 832 free(infotxt); 833 free(prompts); 834 free(echo_on); 835 } 836 837 return (0); 838 } 839 840 int 841 mm_answer_bsdauthrespond(struct ssh *ssh, int sock, struct sshbuf *m) 842 { 843 char *response; 844 int r, authok; 845 846 if (!options.kbd_interactive_authentication) 847 fatal_f("kbd-int authentication not enabled"); 848 if (authctxt->as == NULL) 849 fatal_f("no bsd auth session"); 850 851 if ((r = sshbuf_get_cstring(m, &response, NULL)) != 0) 852 fatal_fr(r, "parse"); 853 authok = options.challenge_response_authentication && 854 auth_userresponse(authctxt->as, response, 0); 855 authctxt->as = NULL; 856 debug3_f("<%s> = <%d>", response, authok); 857 free(response); 858 859 sshbuf_reset(m); 860 if ((r = sshbuf_put_u32(m, authok)) != 0) 861 fatal_fr(r, "assemble"); 862 863 debug3_f("sending authenticated: %d", authok); 864 mm_request_send(sock, MONITOR_ANS_BSDAUTHRESPOND, m); 865 866 auth_method = "keyboard-interactive"; 867 auth_submethod = "bsdauth"; 868 869 return (authok != 0); 870 } 871 872 /* 873 * Check that the key type appears in the supplied pattern list, ignoring 874 * mismatches in the signature algorithm. (Signature algorithm checks are 875 * performed in the unprivileged authentication code). 876 * Returns 1 on success, 0 otherwise. 877 */ 878 static int 879 key_base_type_match(const char *method, const struct sshkey *key, 880 const char *list) 881 { 882 char *s, *l, *ol = xstrdup(list); 883 int found = 0; 884 885 l = ol; 886 for ((s = strsep(&l, ",")); s && *s != '\0'; (s = strsep(&l, ","))) { 887 if (sshkey_type_from_name(s) == key->type) { 888 found = 1; 889 break; 890 } 891 } 892 if (!found) { 893 error("%s key type %s is not in permitted list %s", method, 894 sshkey_ssh_name(key), list); 895 } 896 897 free(ol); 898 return found; 899 } 900 901 int 902 mm_answer_keyallowed(struct ssh *ssh, int sock, struct sshbuf *m) 903 { 904 struct sshkey *key = NULL; 905 char *cuser, *chost; 906 u_int pubkey_auth_attempt; 907 u_int type = 0; 908 int r, allowed = 0; 909 struct sshauthopt *opts = NULL; 910 911 debug3_f("entering"); 912 if ((r = sshbuf_get_u32(m, &type)) != 0 || 913 (r = sshbuf_get_cstring(m, &cuser, NULL)) != 0 || 914 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 || 915 (r = sshkey_froms(m, &key)) != 0 || 916 (r = sshbuf_get_u32(m, &pubkey_auth_attempt)) != 0) 917 fatal_fr(r, "parse"); 918 919 debug3_f("key_from_blob: %p", key); 920 921 if (key != NULL && authctxt->valid) { 922 /* These should not make it past the privsep child */ 923 if (sshkey_type_plain(key->type) == KEY_RSA && 924 (ssh->compat & SSH_BUG_RSASIGMD5) != 0) 925 fatal_f("passed a SSH_BUG_RSASIGMD5 key"); 926 927 switch (type) { 928 case MM_USERKEY: 929 auth_method = "publickey"; 930 if (!options.pubkey_authentication) 931 break; 932 if (auth2_key_already_used(authctxt, key)) 933 break; 934 if (!key_base_type_match(auth_method, key, 935 options.pubkey_accepted_algos)) 936 break; 937 allowed = user_key_allowed(ssh, authctxt->pw, key, 938 pubkey_auth_attempt, &opts); 939 break; 940 case MM_HOSTKEY: 941 auth_method = "hostbased"; 942 if (!options.hostbased_authentication) 943 break; 944 if (auth2_key_already_used(authctxt, key)) 945 break; 946 if (!key_base_type_match(auth_method, key, 947 options.hostbased_accepted_algos)) 948 break; 949 allowed = hostbased_key_allowed(ssh, authctxt->pw, 950 cuser, chost, key); 951 auth2_record_info(authctxt, 952 "client user \"%.100s\", client host \"%.100s\"", 953 cuser, chost); 954 break; 955 default: 956 fatal_f("unknown key type %u", type); 957 break; 958 } 959 } 960 961 debug3_f("%s authentication%s: %s key is %s", auth_method, 962 pubkey_auth_attempt ? "" : " test", 963 (key == NULL || !authctxt->valid) ? "invalid" : sshkey_type(key), 964 allowed ? "allowed" : "not allowed"); 965 966 auth2_record_key(authctxt, 0, key); 967 968 /* clear temporarily storage (used by verify) */ 969 monitor_reset_key_state(); 970 971 if (allowed) { 972 /* Save temporarily for comparison in verify */ 973 if ((r = sshkey_to_blob(key, &key_blob, &key_bloblen)) != 0) 974 fatal_fr(r, "sshkey_to_blob"); 975 key_blobtype = type; 976 key_opts = opts; 977 hostbased_cuser = cuser; 978 hostbased_chost = chost; 979 } else { 980 /* Log failed attempt */ 981 auth_log(ssh, 0, 0, auth_method, NULL); 982 free(cuser); 983 free(chost); 984 } 985 sshkey_free(key); 986 987 sshbuf_reset(m); 988 if ((r = sshbuf_put_u32(m, allowed)) != 0) 989 fatal_fr(r, "assemble"); 990 if (opts != NULL && (r = sshauthopt_serialise(opts, m, 1)) != 0) 991 fatal_fr(r, "sshauthopt_serialise"); 992 mm_request_send(sock, MONITOR_ANS_KEYALLOWED, m); 993 994 if (!allowed) 995 sshauthopt_free(opts); 996 997 return (0); 998 } 999 1000 static int 1001 monitor_valid_userblob(struct ssh *ssh, const u_char *data, u_int datalen) 1002 { 1003 struct sshbuf *b; 1004 const u_char *p; 1005 char *userstyle, *cp; 1006 size_t len; 1007 u_char type; 1008 int r, fail = 0; 1009 1010 if ((b = sshbuf_from(data, datalen)) == NULL) 1011 fatal_f("sshbuf_from"); 1012 1013 if (ssh->compat & SSH_OLD_SESSIONID) { 1014 p = sshbuf_ptr(b); 1015 len = sshbuf_len(b); 1016 if ((session_id2 == NULL) || 1017 (len < session_id2_len) || 1018 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) 1019 fail++; 1020 if ((r = sshbuf_consume(b, session_id2_len)) != 0) 1021 fatal_fr(r, "consume"); 1022 } else { 1023 if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0) 1024 fatal_fr(r, "parse sessionid"); 1025 if ((session_id2 == NULL) || 1026 (len != session_id2_len) || 1027 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) 1028 fail++; 1029 } 1030 if ((r = sshbuf_get_u8(b, &type)) != 0) 1031 fatal_fr(r, "parse type"); 1032 if (type != SSH2_MSG_USERAUTH_REQUEST) 1033 fail++; 1034 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1035 fatal_fr(r, "parse userstyle"); 1036 xasprintf(&userstyle, "%s%s%s", authctxt->user, 1037 authctxt->style ? ":" : "", 1038 authctxt->style ? authctxt->style : ""); 1039 if (strcmp(userstyle, cp) != 0) { 1040 logit("wrong user name passed to monitor: " 1041 "expected %s != %.100s", userstyle, cp); 1042 fail++; 1043 } 1044 free(userstyle); 1045 free(cp); 1046 if ((r = sshbuf_skip_string(b)) != 0 || /* service */ 1047 (r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1048 fatal_fr(r, "parse method"); 1049 if (strcmp("publickey", cp) != 0) 1050 fail++; 1051 free(cp); 1052 if ((r = sshbuf_get_u8(b, &type)) != 0) 1053 fatal_fr(r, "parse pktype"); 1054 if (type == 0) 1055 fail++; 1056 if ((r = sshbuf_skip_string(b)) != 0 || /* pkalg */ 1057 (r = sshbuf_skip_string(b)) != 0) /* pkblob */ 1058 fatal_fr(r, "parse pk"); 1059 if (sshbuf_len(b) != 0) 1060 fail++; 1061 sshbuf_free(b); 1062 return (fail == 0); 1063 } 1064 1065 static int 1066 monitor_valid_hostbasedblob(const u_char *data, u_int datalen, 1067 const char *cuser, const char *chost) 1068 { 1069 struct sshbuf *b; 1070 const u_char *p; 1071 char *cp, *userstyle; 1072 size_t len; 1073 int r, fail = 0; 1074 u_char type; 1075 1076 if ((b = sshbuf_from(data, datalen)) == NULL) 1077 fatal_f("sshbuf_new"); 1078 if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0) 1079 fatal_fr(r, "parse sessionid"); 1080 1081 if ((session_id2 == NULL) || 1082 (len != session_id2_len) || 1083 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) 1084 fail++; 1085 1086 if ((r = sshbuf_get_u8(b, &type)) != 0) 1087 fatal_fr(r, "parse type"); 1088 if (type != SSH2_MSG_USERAUTH_REQUEST) 1089 fail++; 1090 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1091 fatal_fr(r, "parse userstyle"); 1092 xasprintf(&userstyle, "%s%s%s", authctxt->user, 1093 authctxt->style ? ":" : "", 1094 authctxt->style ? authctxt->style : ""); 1095 if (strcmp(userstyle, cp) != 0) { 1096 logit("wrong user name passed to monitor: " 1097 "expected %s != %.100s", userstyle, cp); 1098 fail++; 1099 } 1100 free(userstyle); 1101 free(cp); 1102 if ((r = sshbuf_skip_string(b)) != 0 || /* service */ 1103 (r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1104 fatal_fr(r, "parse method"); 1105 if (strcmp(cp, "hostbased") != 0) 1106 fail++; 1107 free(cp); 1108 if ((r = sshbuf_skip_string(b)) != 0 || /* pkalg */ 1109 (r = sshbuf_skip_string(b)) != 0) /* pkblob */ 1110 fatal_fr(r, "parse pk"); 1111 1112 /* verify client host, strip trailing dot if necessary */ 1113 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1114 fatal_fr(r, "parse host"); 1115 if (((len = strlen(cp)) > 0) && cp[len - 1] == '.') 1116 cp[len - 1] = '\0'; 1117 if (strcmp(cp, chost) != 0) 1118 fail++; 1119 free(cp); 1120 1121 /* verify client user */ 1122 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1123 fatal_fr(r, "parse ruser"); 1124 if (strcmp(cp, cuser) != 0) 1125 fail++; 1126 free(cp); 1127 1128 if (sshbuf_len(b) != 0) 1129 fail++; 1130 sshbuf_free(b); 1131 return (fail == 0); 1132 } 1133 1134 int 1135 mm_answer_keyverify(struct ssh *ssh, int sock, struct sshbuf *m) 1136 { 1137 struct sshkey *key; 1138 const u_char *signature, *data, *blob; 1139 char *sigalg = NULL, *fp = NULL; 1140 size_t signaturelen, datalen, bloblen; 1141 int r, ret, req_presence = 0, req_verify = 0, valid_data = 0; 1142 int encoded_ret; 1143 struct sshkey_sig_details *sig_details = NULL; 1144 1145 if ((r = sshbuf_get_string_direct(m, &blob, &bloblen)) != 0 || 1146 (r = sshbuf_get_string_direct(m, &signature, &signaturelen)) != 0 || 1147 (r = sshbuf_get_string_direct(m, &data, &datalen)) != 0 || 1148 (r = sshbuf_get_cstring(m, &sigalg, NULL)) != 0) 1149 fatal_fr(r, "parse"); 1150 1151 if (hostbased_cuser == NULL || hostbased_chost == NULL || 1152 !monitor_allowed_key(blob, bloblen)) 1153 fatal_f("bad key, not previously allowed"); 1154 1155 /* Empty signature algorithm means NULL. */ 1156 if (*sigalg == '\0') { 1157 free(sigalg); 1158 sigalg = NULL; 1159 } 1160 1161 /* XXX use sshkey_froms here; need to change key_blob, etc. */ 1162 if ((r = sshkey_from_blob(blob, bloblen, &key)) != 0) 1163 fatal_fr(r, "parse key"); 1164 1165 switch (key_blobtype) { 1166 case MM_USERKEY: 1167 valid_data = monitor_valid_userblob(ssh, data, datalen); 1168 auth_method = "publickey"; 1169 break; 1170 case MM_HOSTKEY: 1171 valid_data = monitor_valid_hostbasedblob(data, datalen, 1172 hostbased_cuser, hostbased_chost); 1173 auth_method = "hostbased"; 1174 break; 1175 default: 1176 valid_data = 0; 1177 break; 1178 } 1179 if (!valid_data) 1180 fatal_f("bad %s signature data blob", 1181 key_blobtype == MM_USERKEY ? "userkey" : 1182 (key_blobtype == MM_HOSTKEY ? "hostkey" : "unknown")); 1183 1184 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, 1185 SSH_FP_DEFAULT)) == NULL) 1186 fatal_f("sshkey_fingerprint failed"); 1187 1188 ret = sshkey_verify(key, signature, signaturelen, data, datalen, 1189 sigalg, ssh->compat, &sig_details); 1190 debug3_f("%s %p signature %s%s%s", auth_method, key, 1191 (ret == 0) ? "verified" : "unverified", 1192 (ret != 0) ? ": " : "", (ret != 0) ? ssh_err(ret) : ""); 1193 1194 if (ret == 0 && key_blobtype == MM_USERKEY && sig_details != NULL) { 1195 req_presence = (options.pubkey_auth_options & 1196 PUBKEYAUTH_TOUCH_REQUIRED) || 1197 !key_opts->no_require_user_presence; 1198 if (req_presence && 1199 (sig_details->sk_flags & SSH_SK_USER_PRESENCE_REQD) == 0) { 1200 error("public key %s %s signature for %s%s from %.128s " 1201 "port %d rejected: user presence " 1202 "(authenticator touch) requirement not met ", 1203 sshkey_type(key), fp, 1204 authctxt->valid ? "" : "invalid user ", 1205 authctxt->user, ssh_remote_ipaddr(ssh), 1206 ssh_remote_port(ssh)); 1207 ret = SSH_ERR_SIGNATURE_INVALID; 1208 } 1209 req_verify = (options.pubkey_auth_options & 1210 PUBKEYAUTH_VERIFY_REQUIRED) || key_opts->require_verify; 1211 if (req_verify && 1212 (sig_details->sk_flags & SSH_SK_USER_VERIFICATION_REQD) == 0) { 1213 error("public key %s %s signature for %s%s from %.128s " 1214 "port %d rejected: user verification requirement " 1215 "not met ", sshkey_type(key), fp, 1216 authctxt->valid ? "" : "invalid user ", 1217 authctxt->user, ssh_remote_ipaddr(ssh), 1218 ssh_remote_port(ssh)); 1219 ret = SSH_ERR_SIGNATURE_INVALID; 1220 } 1221 } 1222 auth2_record_key(authctxt, ret == 0, key); 1223 1224 if (key_blobtype == MM_USERKEY) 1225 auth_activate_options(ssh, key_opts); 1226 monitor_reset_key_state(); 1227 1228 sshbuf_reset(m); 1229 1230 /* encode ret != 0 as positive integer, since we're sending u32 */ 1231 encoded_ret = (ret != 0); 1232 if ((r = sshbuf_put_u32(m, encoded_ret)) != 0 || 1233 (r = sshbuf_put_u8(m, sig_details != NULL)) != 0) 1234 fatal_fr(r, "assemble"); 1235 if (sig_details != NULL) { 1236 if ((r = sshbuf_put_u32(m, sig_details->sk_counter)) != 0 || 1237 (r = sshbuf_put_u8(m, sig_details->sk_flags)) != 0) 1238 fatal_fr(r, "assemble sk"); 1239 } 1240 sshkey_sig_details_free(sig_details); 1241 mm_request_send(sock, MONITOR_ANS_KEYVERIFY, m); 1242 1243 free(sigalg); 1244 free(fp); 1245 sshkey_free(key); 1246 1247 return ret == 0; 1248 } 1249 1250 static void 1251 mm_record_login(struct ssh *ssh, Session *s, struct passwd *pw) 1252 { 1253 socklen_t fromlen; 1254 struct sockaddr_storage from; 1255 1256 /* 1257 * Get IP address of client. If the connection is not a socket, let 1258 * the address be 0.0.0.0. 1259 */ 1260 memset(&from, 0, sizeof(from)); 1261 fromlen = sizeof(from); 1262 if (ssh_packet_connection_is_on_socket(ssh)) { 1263 if (getpeername(ssh_packet_get_connection_in(ssh), 1264 (struct sockaddr *)&from, &fromlen) == -1) { 1265 debug("getpeername: %.100s", strerror(errno)); 1266 cleanup_exit(255); 1267 } 1268 } 1269 /* Record that there was a login on that tty from the remote host. */ 1270 record_login(s->pid, s->tty, pw->pw_name, pw->pw_uid, 1271 session_get_remote_name_or_ip(ssh, utmp_len, options.use_dns), 1272 (struct sockaddr *)&from, fromlen); 1273 } 1274 1275 static void 1276 mm_session_close(Session *s) 1277 { 1278 debug3_f("session %d pid %ld", s->self, (long)s->pid); 1279 if (s->ttyfd != -1) { 1280 debug3_f("tty %s ptyfd %d", s->tty, s->ptyfd); 1281 session_pty_cleanup2(s); 1282 } 1283 session_unused(s->self); 1284 } 1285 1286 int 1287 mm_answer_pty(struct ssh *ssh, int sock, struct sshbuf *m) 1288 { 1289 extern struct monitor *pmonitor; 1290 Session *s; 1291 int r, res, fd0; 1292 1293 debug3_f("entering"); 1294 1295 sshbuf_reset(m); 1296 s = session_new(); 1297 if (s == NULL) 1298 goto error; 1299 s->authctxt = authctxt; 1300 s->pw = authctxt->pw; 1301 s->pid = pmonitor->m_pid; 1302 res = pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty)); 1303 if (res == 0) 1304 goto error; 1305 pty_setowner(authctxt->pw, s->tty); 1306 1307 if ((r = sshbuf_put_u32(m, 1)) != 0 || 1308 (r = sshbuf_put_cstring(m, s->tty)) != 0) 1309 fatal_fr(r, "assemble"); 1310 1311 /* We need to trick ttyslot */ 1312 if (dup2(s->ttyfd, 0) == -1) 1313 fatal_f("dup2"); 1314 1315 mm_record_login(ssh, s, authctxt->pw); 1316 1317 /* Now we can close the file descriptor again */ 1318 close(0); 1319 1320 /* send messages generated by record_login */ 1321 if ((r = sshbuf_put_stringb(m, loginmsg)) != 0) 1322 fatal_fr(r, "assemble loginmsg"); 1323 sshbuf_reset(loginmsg); 1324 1325 mm_request_send(sock, MONITOR_ANS_PTY, m); 1326 1327 if (mm_send_fd(sock, s->ptyfd) == -1 || 1328 mm_send_fd(sock, s->ttyfd) == -1) 1329 fatal_f("send fds failed"); 1330 1331 /* make sure nothing uses fd 0 */ 1332 if ((fd0 = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1333 fatal_f("open(/dev/null): %s", strerror(errno)); 1334 if (fd0 != 0) 1335 error_f("fd0 %d != 0", fd0); 1336 1337 /* slave side of pty is not needed */ 1338 close(s->ttyfd); 1339 s->ttyfd = s->ptyfd; 1340 /* no need to dup() because nobody closes ptyfd */ 1341 s->ptymaster = s->ptyfd; 1342 1343 debug3_f("tty %s ptyfd %d", s->tty, s->ttyfd); 1344 1345 return (0); 1346 1347 error: 1348 if (s != NULL) 1349 mm_session_close(s); 1350 if ((r = sshbuf_put_u32(m, 0)) != 0) 1351 fatal_fr(r, "assemble 0"); 1352 mm_request_send(sock, MONITOR_ANS_PTY, m); 1353 return (0); 1354 } 1355 1356 int 1357 mm_answer_pty_cleanup(struct ssh *ssh, int sock, struct sshbuf *m) 1358 { 1359 Session *s; 1360 char *tty; 1361 int r; 1362 1363 debug3_f("entering"); 1364 1365 if ((r = sshbuf_get_cstring(m, &tty, NULL)) != 0) 1366 fatal_fr(r, "parse tty"); 1367 if ((s = session_by_tty(tty)) != NULL) 1368 mm_session_close(s); 1369 sshbuf_reset(m); 1370 free(tty); 1371 return (0); 1372 } 1373 1374 int 1375 mm_answer_term(struct ssh *ssh, int sock, struct sshbuf *req) 1376 { 1377 extern struct monitor *pmonitor; 1378 int res, status; 1379 1380 debug3_f("tearing down sessions"); 1381 1382 /* The child is terminating */ 1383 session_destroy_all(ssh, &mm_session_close); 1384 1385 while (waitpid(pmonitor->m_pid, &status, 0) == -1) 1386 if (errno != EINTR) 1387 exit(1); 1388 1389 res = WIFEXITED(status) ? WEXITSTATUS(status) : 1; 1390 1391 /* Terminate process */ 1392 exit(res); 1393 } 1394 1395 void 1396 monitor_clear_keystate(struct ssh *ssh, struct monitor *pmonitor) 1397 { 1398 ssh_clear_newkeys(ssh, MODE_IN); 1399 ssh_clear_newkeys(ssh, MODE_OUT); 1400 sshbuf_free(child_state); 1401 child_state = NULL; 1402 } 1403 1404 void 1405 monitor_apply_keystate(struct ssh *ssh, struct monitor *pmonitor) 1406 { 1407 struct kex *kex; 1408 int r; 1409 1410 debug3_f("packet_set_state"); 1411 if ((r = ssh_packet_set_state(ssh, child_state)) != 0) 1412 fatal_fr(r, "packet_set_state"); 1413 sshbuf_free(child_state); 1414 child_state = NULL; 1415 if ((kex = ssh->kex) == NULL) 1416 fatal_f("internal error: ssh->kex == NULL"); 1417 if (session_id2_len != sshbuf_len(ssh->kex->session_id)) { 1418 fatal_f("incorrect session id length %zu (expected %u)", 1419 sshbuf_len(ssh->kex->session_id), session_id2_len); 1420 } 1421 if (memcmp(sshbuf_ptr(ssh->kex->session_id), session_id2, 1422 session_id2_len) != 0) 1423 fatal_f("session ID mismatch"); 1424 /* XXX set callbacks */ 1425 #ifdef WITH_OPENSSL 1426 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server; 1427 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server; 1428 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server; 1429 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server; 1430 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server; 1431 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 1432 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 1433 kex->kex[KEX_ECDH_SHA2] = kex_gen_server; 1434 #endif 1435 kex->kex[KEX_C25519_SHA256] = kex_gen_server; 1436 kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server; 1437 kex->load_host_public_key=&get_hostkey_public_by_type; 1438 kex->load_host_private_key=&get_hostkey_private_by_type; 1439 kex->host_key_index=&get_hostkey_index; 1440 kex->sign = sshd_hostkey_sign; 1441 } 1442 1443 /* This function requires careful sanity checking */ 1444 1445 void 1446 mm_get_keystate(struct ssh *ssh, struct monitor *pmonitor) 1447 { 1448 debug3_f("Waiting for new keys"); 1449 1450 if ((child_state = sshbuf_new()) == NULL) 1451 fatal_f("sshbuf_new failed"); 1452 mm_request_receive_expect(pmonitor->m_sendfd, MONITOR_REQ_KEYEXPORT, 1453 child_state); 1454 debug3_f("GOT new keys"); 1455 } 1456 1457 1458 /* XXX */ 1459 1460 #define FD_CLOSEONEXEC(x) do { \ 1461 if (fcntl(x, F_SETFD, FD_CLOEXEC) == -1) \ 1462 fatal("fcntl(%d, F_SETFD)", x); \ 1463 } while (0) 1464 1465 static void 1466 monitor_openfds(struct monitor *mon, int do_logfds) 1467 { 1468 int pair[2]; 1469 #ifdef SO_ZEROIZE 1470 int on = 1; 1471 #endif 1472 1473 if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) 1474 fatal_f("socketpair: %s", strerror(errno)); 1475 #ifdef SO_ZEROIZE 1476 if (setsockopt(pair[0], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1) 1477 error("setsockopt SO_ZEROIZE(0): %.100s", strerror(errno)); 1478 if (setsockopt(pair[1], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1) 1479 error("setsockopt SO_ZEROIZE(1): %.100s", strerror(errno)); 1480 #endif 1481 FD_CLOSEONEXEC(pair[0]); 1482 FD_CLOSEONEXEC(pair[1]); 1483 mon->m_recvfd = pair[0]; 1484 mon->m_sendfd = pair[1]; 1485 1486 if (do_logfds) { 1487 if (pipe(pair) == -1) 1488 fatal_f("pipe: %s", strerror(errno)); 1489 FD_CLOSEONEXEC(pair[0]); 1490 FD_CLOSEONEXEC(pair[1]); 1491 mon->m_log_recvfd = pair[0]; 1492 mon->m_log_sendfd = pair[1]; 1493 } else 1494 mon->m_log_recvfd = mon->m_log_sendfd = -1; 1495 } 1496 1497 #define MM_MEMSIZE 65536 1498 1499 struct monitor * 1500 monitor_init(void) 1501 { 1502 struct monitor *mon; 1503 1504 mon = xcalloc(1, sizeof(*mon)); 1505 monitor_openfds(mon, 1); 1506 1507 return mon; 1508 } 1509 1510 void 1511 monitor_reinit(struct monitor *mon) 1512 { 1513 monitor_openfds(mon, 0); 1514 } 1515 1516 #ifdef GSSAPI 1517 int 1518 mm_answer_gss_setup_ctx(struct ssh *ssh, int sock, struct sshbuf *m) 1519 { 1520 gss_OID_desc goid; 1521 OM_uint32 major; 1522 size_t len; 1523 u_char *p; 1524 int r; 1525 1526 if (!options.gss_authentication) 1527 fatal_f("GSSAPI authentication not enabled"); 1528 1529 if ((r = sshbuf_get_string(m, &p, &len)) != 0) 1530 fatal_fr(r, "parse"); 1531 goid.elements = p; 1532 goid.length = len; 1533 1534 major = ssh_gssapi_server_ctx(&gsscontext, &goid); 1535 1536 free(goid.elements); 1537 1538 sshbuf_reset(m); 1539 if ((r = sshbuf_put_u32(m, major)) != 0) 1540 fatal_fr(r, "assemble"); 1541 1542 mm_request_send(sock, MONITOR_ANS_GSSSETUP, m); 1543 1544 /* Now we have a context, enable the step */ 1545 monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 1); 1546 1547 return (0); 1548 } 1549 1550 int 1551 mm_answer_gss_accept_ctx(struct ssh *ssh, int sock, struct sshbuf *m) 1552 { 1553 gss_buffer_desc in; 1554 gss_buffer_desc out = GSS_C_EMPTY_BUFFER; 1555 OM_uint32 major, minor; 1556 OM_uint32 flags = 0; /* GSI needs this */ 1557 int r; 1558 1559 if (!options.gss_authentication) 1560 fatal_f("GSSAPI authentication not enabled"); 1561 1562 if ((r = ssh_gssapi_get_buffer_desc(m, &in)) != 0) 1563 fatal_fr(r, "ssh_gssapi_get_buffer_desc"); 1564 major = ssh_gssapi_accept_ctx(gsscontext, &in, &out, &flags); 1565 free(in.value); 1566 1567 sshbuf_reset(m); 1568 if ((r = sshbuf_put_u32(m, major)) != 0 || 1569 (r = sshbuf_put_string(m, out.value, out.length)) != 0 || 1570 (r = sshbuf_put_u32(m, flags)) != 0) 1571 fatal_fr(r, "assemble"); 1572 mm_request_send(sock, MONITOR_ANS_GSSSTEP, m); 1573 1574 gss_release_buffer(&minor, &out); 1575 1576 if (major == GSS_S_COMPLETE) { 1577 monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 0); 1578 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1); 1579 monitor_permit(mon_dispatch, MONITOR_REQ_GSSCHECKMIC, 1); 1580 } 1581 return (0); 1582 } 1583 1584 int 1585 mm_answer_gss_checkmic(struct ssh *ssh, int sock, struct sshbuf *m) 1586 { 1587 gss_buffer_desc gssbuf, mic; 1588 OM_uint32 ret; 1589 int r; 1590 1591 if (!options.gss_authentication) 1592 fatal_f("GSSAPI authentication not enabled"); 1593 1594 if ((r = ssh_gssapi_get_buffer_desc(m, &gssbuf)) != 0 || 1595 (r = ssh_gssapi_get_buffer_desc(m, &mic)) != 0) 1596 fatal_fr(r, "ssh_gssapi_get_buffer_desc"); 1597 1598 ret = ssh_gssapi_checkmic(gsscontext, &gssbuf, &mic); 1599 1600 free(gssbuf.value); 1601 free(mic.value); 1602 1603 sshbuf_reset(m); 1604 if ((r = sshbuf_put_u32(m, ret)) != 0) 1605 fatal_fr(r, "assemble"); 1606 1607 mm_request_send(sock, MONITOR_ANS_GSSCHECKMIC, m); 1608 1609 if (!GSS_ERROR(ret)) 1610 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1); 1611 1612 return (0); 1613 } 1614 1615 int 1616 mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m) 1617 { 1618 int r, authenticated; 1619 const char *displayname; 1620 1621 if (!options.gss_authentication) 1622 fatal_f("GSSAPI authentication not enabled"); 1623 1624 authenticated = authctxt->valid && ssh_gssapi_userok(authctxt->user); 1625 1626 sshbuf_reset(m); 1627 if ((r = sshbuf_put_u32(m, authenticated)) != 0) 1628 fatal_fr(r, "assemble"); 1629 1630 debug3_f("sending result %d", authenticated); 1631 mm_request_send(sock, MONITOR_ANS_GSSUSEROK, m); 1632 1633 auth_method = "gssapi-with-mic"; 1634 1635 if ((displayname = ssh_gssapi_displayname()) != NULL) 1636 auth2_record_info(authctxt, "%s", displayname); 1637 1638 /* Monitor loop will terminate if authenticated */ 1639 return (authenticated); 1640 } 1641 #endif /* GSSAPI */ 1642 1643