1 /* $OpenBSD: monitor.c,v 1.167 2017/02/03 23:05:57 djm Exp $ */ 2 /* 3 * Copyright 2002 Niels Provos <provos (at) citi.umich.edu> 4 * Copyright 2002 Markus Friedl <markus (at) openbsd.org> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #include "includes.h" 29 30 #include <sys/types.h> 31 #include <sys/socket.h> 32 #include "openbsd-compat/sys-tree.h" 33 #include <sys/wait.h> 34 35 #include <errno.h> 36 #include <fcntl.h> 37 #include <limits.h> 38 #ifdef HAVE_PATHS_H 39 #include <paths.h> 40 #endif 41 #include <pwd.h> 42 #include <signal.h> 43 #ifdef HAVE_STDINT_H 44 #include <stdint.h> 45 #endif 46 #include <stdlib.h> 47 #include <string.h> 48 #include <stdarg.h> 49 #include <stdio.h> 50 #include <unistd.h> 51 #ifdef HAVE_POLL_H 52 #include <poll.h> 53 #else 54 # ifdef HAVE_SYS_POLL_H 55 # include <sys/poll.h> 56 # endif 57 #endif 58 59 #ifdef SKEY 60 #include <skey.h> 61 #endif 62 63 #ifdef WITH_OPENSSL 64 #include <openssl/dh.h> 65 #endif 66 67 #include "openbsd-compat/sys-queue.h" 68 #include "atomicio.h" 69 #include "xmalloc.h" 70 #include "ssh.h" 71 #include "key.h" 72 #include "buffer.h" 73 #include "hostfile.h" 74 #include "auth.h" 75 #include "cipher.h" 76 #include "kex.h" 77 #include "dh.h" 78 #include "auth-pam.h" 79 #ifdef TARGET_OS_MAC /* XXX Broken krb5 headers on Mac */ 80 #undef TARGET_OS_MAC 81 #include "zlib.h" 82 #define TARGET_OS_MAC 1 83 #else 84 #include "zlib.h" 85 #endif 86 #include "packet.h" 87 #include "auth-options.h" 88 #include "sshpty.h" 89 #include "channels.h" 90 #include "session.h" 91 #include "sshlogin.h" 92 #include "canohost.h" 93 #include "log.h" 94 #include "misc.h" 95 #include "servconf.h" 96 #include "monitor.h" 97 #ifdef GSSAPI 98 #include "ssh-gss.h" 99 #endif 100 #include "monitor_wrap.h" 101 #include "monitor_fdpass.h" 102 #include "compat.h" 103 #include "ssh2.h" 104 #include "authfd.h" 105 #include "match.h" 106 #include "ssherr.h" 107 108 #ifdef GSSAPI 109 static Gssctxt *gsscontext = NULL; 110 #endif 111 112 /* Imports */ 113 extern ServerOptions options; 114 extern u_int utmp_len; 115 extern u_char session_id[]; 116 extern Buffer auth_debug; 117 extern int auth_debug_init; 118 extern Buffer loginmsg; 119 120 /* State exported from the child */ 121 static struct sshbuf *child_state; 122 123 /* Functions on the monitor that answer unprivileged requests */ 124 125 int mm_answer_moduli(int, Buffer *); 126 int mm_answer_sign(int, Buffer *); 127 int mm_answer_pwnamallow(int, Buffer *); 128 int mm_answer_auth2_read_banner(int, Buffer *); 129 int mm_answer_authserv(int, Buffer *); 130 int mm_answer_authpassword(int, Buffer *); 131 int mm_answer_bsdauthquery(int, Buffer *); 132 int mm_answer_bsdauthrespond(int, Buffer *); 133 int mm_answer_skeyquery(int, Buffer *); 134 int mm_answer_skeyrespond(int, Buffer *); 135 int mm_answer_keyallowed(int, Buffer *); 136 int mm_answer_keyverify(int, Buffer *); 137 int mm_answer_pty(int, Buffer *); 138 int mm_answer_pty_cleanup(int, Buffer *); 139 int mm_answer_term(int, Buffer *); 140 int mm_answer_rsa_keyallowed(int, Buffer *); 141 int mm_answer_rsa_challenge(int, Buffer *); 142 int mm_answer_rsa_response(int, Buffer *); 143 int mm_answer_sesskey(int, Buffer *); 144 int mm_answer_sessid(int, Buffer *); 145 146 #ifdef USE_PAM 147 int mm_answer_pam_start(int, Buffer *); 148 int mm_answer_pam_account(int, Buffer *); 149 int mm_answer_pam_init_ctx(int, Buffer *); 150 int mm_answer_pam_query(int, Buffer *); 151 int mm_answer_pam_respond(int, Buffer *); 152 int mm_answer_pam_free_ctx(int, Buffer *); 153 #endif 154 155 #ifdef GSSAPI 156 int mm_answer_gss_setup_ctx(int, Buffer *); 157 int mm_answer_gss_accept_ctx(int, Buffer *); 158 int mm_answer_gss_userok(int, Buffer *); 159 int mm_answer_gss_checkmic(int, Buffer *); 160 #endif 161 162 #ifdef SSH_AUDIT_EVENTS 163 int mm_answer_audit_event(int, Buffer *); 164 int mm_answer_audit_command(int, Buffer *); 165 #endif 166 167 static int monitor_read_log(struct monitor *); 168 169 static Authctxt *authctxt; 170 171 /* local state for key verify */ 172 static u_char *key_blob = NULL; 173 static u_int key_bloblen = 0; 174 static int key_blobtype = MM_NOKEY; 175 static char *hostbased_cuser = NULL; 176 static char *hostbased_chost = NULL; 177 static char *auth_method = "unknown"; 178 static char *auth_submethod = NULL; 179 static u_int session_id2_len = 0; 180 static u_char *session_id2 = NULL; 181 static pid_t monitor_child_pid; 182 183 struct mon_table { 184 enum monitor_reqtype type; 185 int flags; 186 int (*f)(int, Buffer *); 187 }; 188 189 #define MON_ISAUTH 0x0004 /* Required for Authentication */ 190 #define MON_AUTHDECIDE 0x0008 /* Decides Authentication */ 191 #define MON_ONCE 0x0010 /* Disable after calling */ 192 #define MON_ALOG 0x0020 /* Log auth attempt without authenticating */ 193 194 #define MON_AUTH (MON_ISAUTH|MON_AUTHDECIDE) 195 196 #define MON_PERMIT 0x1000 /* Request is permitted */ 197 198 struct mon_table mon_dispatch_proto20[] = { 199 #ifdef WITH_OPENSSL 200 {MONITOR_REQ_MODULI, MON_ONCE, mm_answer_moduli}, 201 #endif 202 {MONITOR_REQ_SIGN, MON_ONCE, mm_answer_sign}, 203 {MONITOR_REQ_PWNAM, MON_ONCE, mm_answer_pwnamallow}, 204 {MONITOR_REQ_AUTHSERV, MON_ONCE, mm_answer_authserv}, 205 {MONITOR_REQ_AUTH2_READ_BANNER, MON_ONCE, mm_answer_auth2_read_banner}, 206 {MONITOR_REQ_AUTHPASSWORD, MON_AUTH, mm_answer_authpassword}, 207 #ifdef USE_PAM 208 {MONITOR_REQ_PAM_START, MON_ONCE, mm_answer_pam_start}, 209 {MONITOR_REQ_PAM_ACCOUNT, 0, mm_answer_pam_account}, 210 {MONITOR_REQ_PAM_INIT_CTX, MON_ONCE, mm_answer_pam_init_ctx}, 211 {MONITOR_REQ_PAM_QUERY, 0, mm_answer_pam_query}, 212 {MONITOR_REQ_PAM_RESPOND, MON_ONCE, mm_answer_pam_respond}, 213 {MONITOR_REQ_PAM_FREE_CTX, MON_ONCE|MON_AUTHDECIDE, mm_answer_pam_free_ctx}, 214 #endif 215 #ifdef SSH_AUDIT_EVENTS 216 {MONITOR_REQ_AUDIT_EVENT, MON_PERMIT, mm_answer_audit_event}, 217 #endif 218 #ifdef BSD_AUTH 219 {MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery}, 220 {MONITOR_REQ_BSDAUTHRESPOND, MON_AUTH, mm_answer_bsdauthrespond}, 221 #endif 222 #ifdef SKEY 223 {MONITOR_REQ_SKEYQUERY, MON_ISAUTH, mm_answer_skeyquery}, 224 {MONITOR_REQ_SKEYRESPOND, MON_AUTH, mm_answer_skeyrespond}, 225 #endif 226 {MONITOR_REQ_KEYALLOWED, MON_ISAUTH, mm_answer_keyallowed}, 227 {MONITOR_REQ_KEYVERIFY, MON_AUTH, mm_answer_keyverify}, 228 #ifdef GSSAPI 229 {MONITOR_REQ_GSSSETUP, MON_ISAUTH, mm_answer_gss_setup_ctx}, 230 {MONITOR_REQ_GSSSTEP, 0, mm_answer_gss_accept_ctx}, 231 {MONITOR_REQ_GSSUSEROK, MON_ONCE|MON_AUTHDECIDE, mm_answer_gss_userok}, 232 {MONITOR_REQ_GSSCHECKMIC, MON_ONCE, mm_answer_gss_checkmic}, 233 #endif 234 {0, 0, NULL} 235 }; 236 237 struct mon_table mon_dispatch_postauth20[] = { 238 #ifdef WITH_OPENSSL 239 {MONITOR_REQ_MODULI, 0, mm_answer_moduli}, 240 #endif 241 {MONITOR_REQ_SIGN, 0, mm_answer_sign}, 242 {MONITOR_REQ_PTY, 0, mm_answer_pty}, 243 {MONITOR_REQ_PTYCLEANUP, 0, mm_answer_pty_cleanup}, 244 {MONITOR_REQ_TERM, 0, mm_answer_term}, 245 #ifdef SSH_AUDIT_EVENTS 246 {MONITOR_REQ_AUDIT_EVENT, MON_PERMIT, mm_answer_audit_event}, 247 {MONITOR_REQ_AUDIT_COMMAND, MON_PERMIT, mm_answer_audit_command}, 248 #endif 249 {0, 0, NULL} 250 }; 251 252 struct mon_table *mon_dispatch; 253 254 /* Specifies if a certain message is allowed at the moment */ 255 256 static void 257 monitor_permit(struct mon_table *ent, enum monitor_reqtype type, int permit) 258 { 259 while (ent->f != NULL) { 260 if (ent->type == type) { 261 ent->flags &= ~MON_PERMIT; 262 ent->flags |= permit ? MON_PERMIT : 0; 263 return; 264 } 265 ent++; 266 } 267 } 268 269 static void 270 monitor_permit_authentications(int permit) 271 { 272 struct mon_table *ent = mon_dispatch; 273 274 while (ent->f != NULL) { 275 if (ent->flags & MON_AUTH) { 276 ent->flags &= ~MON_PERMIT; 277 ent->flags |= permit ? MON_PERMIT : 0; 278 } 279 ent++; 280 } 281 } 282 283 void 284 monitor_child_preauth(Authctxt *_authctxt, struct monitor *pmonitor) 285 { 286 struct ssh *ssh = active_state; /* XXX */ 287 struct mon_table *ent; 288 int authenticated = 0, partial = 0; 289 290 debug3("preauth child monitor started"); 291 292 close(pmonitor->m_recvfd); 293 close(pmonitor->m_log_sendfd); 294 pmonitor->m_log_sendfd = pmonitor->m_recvfd = -1; 295 296 authctxt = _authctxt; 297 memset(authctxt, 0, sizeof(*authctxt)); 298 299 authctxt->loginmsg = &loginmsg; 300 301 mon_dispatch = mon_dispatch_proto20; 302 /* Permit requests for moduli and signatures */ 303 monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); 304 monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); 305 306 /* The first few requests do not require asynchronous access */ 307 while (!authenticated) { 308 partial = 0; 309 auth_method = "unknown"; 310 auth_submethod = NULL; 311 authenticated = (monitor_read(pmonitor, mon_dispatch, &ent) == 1); 312 313 /* Special handling for multiple required authentications */ 314 if (options.num_auth_methods != 0) { 315 if (authenticated && 316 !auth2_update_methods_lists(authctxt, 317 auth_method, auth_submethod)) { 318 debug3("%s: method %s: partial", __func__, 319 auth_method); 320 authenticated = 0; 321 partial = 1; 322 } 323 } 324 325 if (authenticated) { 326 if (!(ent->flags & MON_AUTHDECIDE)) 327 fatal("%s: unexpected authentication from %d", 328 __func__, ent->type); 329 if (authctxt->pw->pw_uid == 0 && 330 !auth_root_allowed(auth_method)) 331 authenticated = 0; 332 #ifdef USE_PAM 333 /* PAM needs to perform account checks after auth */ 334 if (options.use_pam && authenticated) { 335 Buffer m; 336 337 buffer_init(&m); 338 mm_request_receive_expect(pmonitor->m_sendfd, 339 MONITOR_REQ_PAM_ACCOUNT, &m); 340 authenticated = mm_answer_pam_account(pmonitor->m_sendfd, &m); 341 buffer_free(&m); 342 } 343 #endif 344 } 345 if (ent->flags & (MON_AUTHDECIDE|MON_ALOG)) { 346 auth_log(authctxt, authenticated, partial, 347 auth_method, auth_submethod); 348 if (!partial && !authenticated) 349 authctxt->failures++; 350 } 351 } 352 353 if (!authctxt->valid) 354 fatal("%s: authenticated invalid user", __func__); 355 if (strcmp(auth_method, "unknown") == 0) 356 fatal("%s: authentication method name unknown", __func__); 357 358 debug("%s: %s has been authenticated by privileged process", 359 __func__, authctxt->user); 360 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 361 362 mm_get_keystate(pmonitor); 363 364 /* Drain any buffered messages from the child */ 365 while (pmonitor->m_log_recvfd != -1 && monitor_read_log(pmonitor) == 0) 366 ; 367 368 close(pmonitor->m_sendfd); 369 close(pmonitor->m_log_recvfd); 370 pmonitor->m_sendfd = pmonitor->m_log_recvfd = -1; 371 } 372 373 static void 374 monitor_set_child_handler(pid_t pid) 375 { 376 monitor_child_pid = pid; 377 } 378 379 static void 380 monitor_child_handler(int sig) 381 { 382 kill(monitor_child_pid, sig); 383 } 384 385 void 386 monitor_child_postauth(struct monitor *pmonitor) 387 { 388 close(pmonitor->m_recvfd); 389 pmonitor->m_recvfd = -1; 390 391 monitor_set_child_handler(pmonitor->m_pid); 392 signal(SIGHUP, &monitor_child_handler); 393 signal(SIGTERM, &monitor_child_handler); 394 signal(SIGINT, &monitor_child_handler); 395 #ifdef SIGXFSZ 396 signal(SIGXFSZ, SIG_IGN); 397 #endif 398 399 mon_dispatch = mon_dispatch_postauth20; 400 401 /* Permit requests for moduli and signatures */ 402 monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); 403 monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); 404 monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1); 405 406 if (!no_pty_flag) { 407 monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1); 408 monitor_permit(mon_dispatch, MONITOR_REQ_PTYCLEANUP, 1); 409 } 410 411 for (;;) 412 monitor_read(pmonitor, mon_dispatch, NULL); 413 } 414 415 static int 416 monitor_read_log(struct monitor *pmonitor) 417 { 418 Buffer logmsg; 419 u_int len, level; 420 char *msg; 421 422 buffer_init(&logmsg); 423 424 /* Read length */ 425 buffer_append_space(&logmsg, 4); 426 if (atomicio(read, pmonitor->m_log_recvfd, 427 buffer_ptr(&logmsg), buffer_len(&logmsg)) != buffer_len(&logmsg)) { 428 if (errno == EPIPE) { 429 buffer_free(&logmsg); 430 debug("%s: child log fd closed", __func__); 431 close(pmonitor->m_log_recvfd); 432 pmonitor->m_log_recvfd = -1; 433 return -1; 434 } 435 fatal("%s: log fd read: %s", __func__, strerror(errno)); 436 } 437 len = buffer_get_int(&logmsg); 438 if (len <= 4 || len > 8192) 439 fatal("%s: invalid log message length %u", __func__, len); 440 441 /* Read severity, message */ 442 buffer_clear(&logmsg); 443 buffer_append_space(&logmsg, len); 444 if (atomicio(read, pmonitor->m_log_recvfd, 445 buffer_ptr(&logmsg), buffer_len(&logmsg)) != buffer_len(&logmsg)) 446 fatal("%s: log fd read: %s", __func__, strerror(errno)); 447 448 /* Log it */ 449 level = buffer_get_int(&logmsg); 450 msg = buffer_get_string(&logmsg, NULL); 451 if (log_level_name(level) == NULL) 452 fatal("%s: invalid log level %u (corrupted message?)", 453 __func__, level); 454 do_log2(level, "%s [preauth]", msg); 455 456 buffer_free(&logmsg); 457 free(msg); 458 459 return 0; 460 } 461 462 int 463 monitor_read(struct monitor *pmonitor, struct mon_table *ent, 464 struct mon_table **pent) 465 { 466 Buffer m; 467 int ret; 468 u_char type; 469 struct pollfd pfd[2]; 470 471 for (;;) { 472 memset(&pfd, 0, sizeof(pfd)); 473 pfd[0].fd = pmonitor->m_sendfd; 474 pfd[0].events = POLLIN; 475 pfd[1].fd = pmonitor->m_log_recvfd; 476 pfd[1].events = pfd[1].fd == -1 ? 0 : POLLIN; 477 if (poll(pfd, pfd[1].fd == -1 ? 1 : 2, -1) == -1) { 478 if (errno == EINTR || errno == EAGAIN) 479 continue; 480 fatal("%s: poll: %s", __func__, strerror(errno)); 481 } 482 if (pfd[1].revents) { 483 /* 484 * Drain all log messages before processing next 485 * monitor request. 486 */ 487 monitor_read_log(pmonitor); 488 continue; 489 } 490 if (pfd[0].revents) 491 break; /* Continues below */ 492 } 493 494 buffer_init(&m); 495 496 mm_request_receive(pmonitor->m_sendfd, &m); 497 type = buffer_get_char(&m); 498 499 debug3("%s: checking request %d", __func__, type); 500 501 while (ent->f != NULL) { 502 if (ent->type == type) 503 break; 504 ent++; 505 } 506 507 if (ent->f != NULL) { 508 if (!(ent->flags & MON_PERMIT)) 509 fatal("%s: unpermitted request %d", __func__, 510 type); 511 ret = (*ent->f)(pmonitor->m_sendfd, &m); 512 buffer_free(&m); 513 514 /* The child may use this request only once, disable it */ 515 if (ent->flags & MON_ONCE) { 516 debug2("%s: %d used once, disabling now", __func__, 517 type); 518 ent->flags &= ~MON_PERMIT; 519 } 520 521 if (pent != NULL) 522 *pent = ent; 523 524 return ret; 525 } 526 527 fatal("%s: unsupported request: %d", __func__, type); 528 529 /* NOTREACHED */ 530 return (-1); 531 } 532 533 /* allowed key state */ 534 static int 535 monitor_allowed_key(u_char *blob, u_int bloblen) 536 { 537 /* make sure key is allowed */ 538 if (key_blob == NULL || key_bloblen != bloblen || 539 timingsafe_bcmp(key_blob, blob, key_bloblen)) 540 return (0); 541 return (1); 542 } 543 544 static void 545 monitor_reset_key_state(void) 546 { 547 /* reset state */ 548 free(key_blob); 549 free(hostbased_cuser); 550 free(hostbased_chost); 551 key_blob = NULL; 552 key_bloblen = 0; 553 key_blobtype = MM_NOKEY; 554 hostbased_cuser = NULL; 555 hostbased_chost = NULL; 556 } 557 558 #ifdef WITH_OPENSSL 559 int 560 mm_answer_moduli(int sock, Buffer *m) 561 { 562 DH *dh; 563 int min, want, max; 564 565 min = buffer_get_int(m); 566 want = buffer_get_int(m); 567 max = buffer_get_int(m); 568 569 debug3("%s: got parameters: %d %d %d", 570 __func__, min, want, max); 571 /* We need to check here, too, in case the child got corrupted */ 572 if (max < min || want < min || max < want) 573 fatal("%s: bad parameters: %d %d %d", 574 __func__, min, want, max); 575 576 buffer_clear(m); 577 578 dh = choose_dh(min, want, max); 579 if (dh == NULL) { 580 buffer_put_char(m, 0); 581 return (0); 582 } else { 583 /* Send first bignum */ 584 buffer_put_char(m, 1); 585 buffer_put_bignum2(m, dh->p); 586 buffer_put_bignum2(m, dh->g); 587 588 DH_free(dh); 589 } 590 mm_request_send(sock, MONITOR_ANS_MODULI, m); 591 return (0); 592 } 593 #endif 594 595 int 596 mm_answer_sign(int sock, Buffer *m) 597 { 598 struct ssh *ssh = active_state; /* XXX */ 599 extern int auth_sock; /* XXX move to state struct? */ 600 struct sshkey *key; 601 struct sshbuf *sigbuf = NULL; 602 u_char *p = NULL, *signature = NULL; 603 char *alg = NULL; 604 size_t datlen, siglen, alglen; 605 int r, is_proof = 0; 606 u_int keyid; 607 const char proof_req[] = "hostkeys-prove-00 (at) openssh.com"; 608 609 debug3("%s", __func__); 610 611 if ((r = sshbuf_get_u32(m, &keyid)) != 0 || 612 (r = sshbuf_get_string(m, &p, &datlen)) != 0 || 613 (r = sshbuf_get_cstring(m, &alg, &alglen)) != 0) 614 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 615 if (keyid > INT_MAX) 616 fatal("%s: invalid key ID", __func__); 617 618 /* 619 * Supported KEX types use SHA1 (20 bytes), SHA256 (32 bytes), 620 * SHA384 (48 bytes) and SHA512 (64 bytes). 621 * 622 * Otherwise, verify the signature request is for a hostkey 623 * proof. 624 * 625 * XXX perform similar check for KEX signature requests too? 626 * it's not trivial, since what is signed is the hash, rather 627 * than the full kex structure... 628 */ 629 if (datlen != 20 && datlen != 32 && datlen != 48 && datlen != 64) { 630 /* 631 * Construct expected hostkey proof and compare it to what 632 * the client sent us. 633 */ 634 if (session_id2_len == 0) /* hostkeys is never first */ 635 fatal("%s: bad data length: %zu", __func__, datlen); 636 if ((key = get_hostkey_public_by_index(keyid, ssh)) == NULL) 637 fatal("%s: no hostkey for index %d", __func__, keyid); 638 if ((sigbuf = sshbuf_new()) == NULL) 639 fatal("%s: sshbuf_new", __func__); 640 if ((r = sshbuf_put_cstring(sigbuf, proof_req)) != 0 || 641 (r = sshbuf_put_string(sigbuf, session_id2, 642 session_id2_len)) != 0 || 643 (r = sshkey_puts(key, sigbuf)) != 0) 644 fatal("%s: couldn't prepare private key " 645 "proof buffer: %s", __func__, ssh_err(r)); 646 if (datlen != sshbuf_len(sigbuf) || 647 memcmp(p, sshbuf_ptr(sigbuf), sshbuf_len(sigbuf)) != 0) 648 fatal("%s: bad data length: %zu, hostkey proof len %zu", 649 __func__, datlen, sshbuf_len(sigbuf)); 650 sshbuf_free(sigbuf); 651 is_proof = 1; 652 } 653 654 /* save session id, it will be passed on the first call */ 655 if (session_id2_len == 0) { 656 session_id2_len = datlen; 657 session_id2 = xmalloc(session_id2_len); 658 memcpy(session_id2, p, session_id2_len); 659 } 660 661 if ((key = get_hostkey_by_index(keyid)) != NULL) { 662 if ((r = sshkey_sign(key, &signature, &siglen, p, datlen, alg, 663 datafellows)) != 0) 664 fatal("%s: sshkey_sign failed: %s", 665 __func__, ssh_err(r)); 666 } else if ((key = get_hostkey_public_by_index(keyid, ssh)) != NULL && 667 auth_sock > 0) { 668 if ((r = ssh_agent_sign(auth_sock, key, &signature, &siglen, 669 p, datlen, alg, datafellows)) != 0) { 670 fatal("%s: ssh_agent_sign failed: %s", 671 __func__, ssh_err(r)); 672 } 673 } else 674 fatal("%s: no hostkey from index %d", __func__, keyid); 675 676 debug3("%s: %s signature %p(%zu)", __func__, 677 is_proof ? "KEX" : "hostkey proof", signature, siglen); 678 679 sshbuf_reset(m); 680 if ((r = sshbuf_put_string(m, signature, siglen)) != 0) 681 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 682 683 free(alg); 684 free(p); 685 free(signature); 686 687 mm_request_send(sock, MONITOR_ANS_SIGN, m); 688 689 /* Turn on permissions for getpwnam */ 690 monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1); 691 692 return (0); 693 } 694 695 /* Retrieves the password entry and also checks if the user is permitted */ 696 697 int 698 mm_answer_pwnamallow(int sock, Buffer *m) 699 { 700 struct ssh *ssh = active_state; /* XXX */ 701 char *username; 702 struct passwd *pwent; 703 int allowed = 0; 704 u_int i; 705 706 debug3("%s", __func__); 707 708 if (authctxt->attempt++ != 0) 709 fatal("%s: multiple attempts for getpwnam", __func__); 710 711 username = buffer_get_string(m, NULL); 712 713 pwent = getpwnamallow(username); 714 715 authctxt->user = xstrdup(username); 716 setproctitle("%s [priv]", pwent ? username : "unknown"); 717 free(username); 718 719 buffer_clear(m); 720 721 if (pwent == NULL) { 722 buffer_put_char(m, 0); 723 authctxt->pw = fakepw(); 724 goto out; 725 } 726 727 allowed = 1; 728 authctxt->pw = pwent; 729 authctxt->valid = 1; 730 731 buffer_put_char(m, 1); 732 buffer_put_string(m, pwent, sizeof(struct passwd)); 733 buffer_put_cstring(m, pwent->pw_name); 734 buffer_put_cstring(m, "*"); 735 #ifdef HAVE_STRUCT_PASSWD_PW_GECOS 736 buffer_put_cstring(m, pwent->pw_gecos); 737 #endif 738 #ifdef HAVE_STRUCT_PASSWD_PW_CLASS 739 buffer_put_cstring(m, pwent->pw_class); 740 #endif 741 buffer_put_cstring(m, pwent->pw_dir); 742 buffer_put_cstring(m, pwent->pw_shell); 743 744 out: 745 ssh_packet_set_log_preamble(ssh, "%suser %s", 746 authctxt->valid ? "authenticating" : "invalid ", authctxt->user); 747 buffer_put_string(m, &options, sizeof(options)); 748 749 #define M_CP_STROPT(x) do { \ 750 if (options.x != NULL) \ 751 buffer_put_cstring(m, options.x); \ 752 } while (0) 753 #define M_CP_STRARRAYOPT(x, nx) do { \ 754 for (i = 0; i < options.nx; i++) \ 755 buffer_put_cstring(m, options.x[i]); \ 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 /* Create valid auth method lists */ 763 if (auth2_setup_methods_lists(authctxt) != 0) { 764 /* 765 * The monitor will continue long enough to let the child 766 * run to it's packet_disconnect(), but it must not allow any 767 * authentication to succeed. 768 */ 769 debug("%s: no valid authentication method lists", __func__); 770 } 771 772 debug3("%s: sending MONITOR_ANS_PWNAM: %d", __func__, allowed); 773 mm_request_send(sock, MONITOR_ANS_PWNAM, m); 774 775 /* Allow service/style information on the auth context */ 776 monitor_permit(mon_dispatch, MONITOR_REQ_AUTHSERV, 1); 777 monitor_permit(mon_dispatch, MONITOR_REQ_AUTH2_READ_BANNER, 1); 778 779 #ifdef USE_PAM 780 if (options.use_pam) 781 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_START, 1); 782 #endif 783 784 return (0); 785 } 786 787 int mm_answer_auth2_read_banner(int sock, Buffer *m) 788 { 789 char *banner; 790 791 buffer_clear(m); 792 banner = auth2_read_banner(); 793 buffer_put_cstring(m, banner != NULL ? banner : ""); 794 mm_request_send(sock, MONITOR_ANS_AUTH2_READ_BANNER, m); 795 free(banner); 796 797 return (0); 798 } 799 800 int 801 mm_answer_authserv(int sock, Buffer *m) 802 { 803 monitor_permit_authentications(1); 804 805 authctxt->service = buffer_get_string(m, NULL); 806 authctxt->style = buffer_get_string(m, NULL); 807 debug3("%s: service=%s, style=%s", 808 __func__, authctxt->service, authctxt->style); 809 810 if (strlen(authctxt->style) == 0) { 811 free(authctxt->style); 812 authctxt->style = NULL; 813 } 814 815 return (0); 816 } 817 818 int 819 mm_answer_authpassword(int sock, Buffer *m) 820 { 821 static int call_count; 822 char *passwd; 823 int authenticated; 824 u_int plen; 825 826 if (!options.password_authentication) 827 fatal("%s: password authentication not enabled", __func__); 828 passwd = buffer_get_string(m, &plen); 829 #if !defined(ANDROID) 830 /* Only authenticate if the context is valid */ 831 authenticated = options.password_authentication && 832 auth_password(authctxt, passwd); 833 #else 834 /* no password authentication in Android. */ 835 authenticated = 0; 836 #endif 837 explicit_bzero(passwd, strlen(passwd)); 838 free(passwd); 839 840 buffer_clear(m); 841 buffer_put_int(m, authenticated); 842 #ifdef USE_PAM 843 buffer_put_int(m, sshpam_get_maxtries_reached()); 844 #endif 845 846 debug3("%s: sending result %d", __func__, authenticated); 847 mm_request_send(sock, MONITOR_ANS_AUTHPASSWORD, m); 848 849 call_count++; 850 if (plen == 0 && call_count == 1) 851 auth_method = "none"; 852 else 853 auth_method = "password"; 854 855 /* Causes monitor loop to terminate if authenticated */ 856 return (authenticated); 857 } 858 859 #ifdef BSD_AUTH 860 int 861 mm_answer_bsdauthquery(int sock, Buffer *m) 862 { 863 char *name, *infotxt; 864 u_int numprompts; 865 u_int *echo_on; 866 char **prompts; 867 u_int success; 868 869 if (!options.kbd_interactive_authentication) 870 fatal("%s: kbd-int authentication not enabled", __func__); 871 success = bsdauth_query(authctxt, &name, &infotxt, &numprompts, 872 &prompts, &echo_on) < 0 ? 0 : 1; 873 874 buffer_clear(m); 875 buffer_put_int(m, success); 876 if (success) 877 buffer_put_cstring(m, prompts[0]); 878 879 debug3("%s: sending challenge success: %u", __func__, success); 880 mm_request_send(sock, MONITOR_ANS_BSDAUTHQUERY, m); 881 882 if (success) { 883 free(name); 884 free(infotxt); 885 free(prompts); 886 free(echo_on); 887 } 888 889 return (0); 890 } 891 892 int 893 mm_answer_bsdauthrespond(int sock, Buffer *m) 894 { 895 char *response; 896 int authok; 897 898 if (!options.kbd_interactive_authentication) 899 fatal("%s: kbd-int authentication not enabled", __func__); 900 if (authctxt->as == NULL) 901 fatal("%s: no bsd auth session", __func__); 902 903 response = buffer_get_string(m, NULL); 904 authok = options.challenge_response_authentication && 905 auth_userresponse(authctxt->as, response, 0); 906 authctxt->as = NULL; 907 debug3("%s: <%s> = <%d>", __func__, response, authok); 908 free(response); 909 910 buffer_clear(m); 911 buffer_put_int(m, authok); 912 913 debug3("%s: sending authenticated: %d", __func__, authok); 914 mm_request_send(sock, MONITOR_ANS_BSDAUTHRESPOND, m); 915 916 auth_method = "keyboard-interactive"; 917 auth_submethod = "bsdauth"; 918 919 return (authok != 0); 920 } 921 #endif 922 923 #ifdef SKEY 924 int 925 mm_answer_skeyquery(int sock, Buffer *m) 926 { 927 struct skey skey; 928 char challenge[1024]; 929 u_int success; 930 931 success = _compat_skeychallenge(&skey, authctxt->user, challenge, 932 sizeof(challenge)) < 0 ? 0 : 1; 933 934 buffer_clear(m); 935 buffer_put_int(m, success); 936 if (success) 937 buffer_put_cstring(m, challenge); 938 939 debug3("%s: sending challenge success: %u", __func__, success); 940 mm_request_send(sock, MONITOR_ANS_SKEYQUERY, m); 941 942 return (0); 943 } 944 945 int 946 mm_answer_skeyrespond(int sock, Buffer *m) 947 { 948 char *response; 949 int authok; 950 951 response = buffer_get_string(m, NULL); 952 953 authok = (options.challenge_response_authentication && 954 authctxt->valid && 955 skey_haskey(authctxt->pw->pw_name) == 0 && 956 skey_passcheck(authctxt->pw->pw_name, response) != -1); 957 958 free(response); 959 960 buffer_clear(m); 961 buffer_put_int(m, authok); 962 963 debug3("%s: sending authenticated: %d", __func__, authok); 964 mm_request_send(sock, MONITOR_ANS_SKEYRESPOND, m); 965 966 auth_method = "keyboard-interactive"; 967 auth_submethod = "skey"; 968 969 return (authok != 0); 970 } 971 #endif 972 973 #ifdef USE_PAM 974 int 975 mm_answer_pam_start(int sock, Buffer *m) 976 { 977 if (!options.use_pam) 978 fatal("UsePAM not set, but ended up in %s anyway", __func__); 979 980 start_pam(authctxt); 981 982 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_ACCOUNT, 1); 983 if (options.kbd_interactive_authentication) 984 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_INIT_CTX, 1); 985 986 return (0); 987 } 988 989 int 990 mm_answer_pam_account(int sock, Buffer *m) 991 { 992 u_int ret; 993 994 if (!options.use_pam) 995 fatal("%s: PAM not enabled", __func__); 996 997 ret = do_pam_account(); 998 999 buffer_put_int(m, ret); 1000 buffer_put_string(m, buffer_ptr(&loginmsg), buffer_len(&loginmsg)); 1001 1002 mm_request_send(sock, MONITOR_ANS_PAM_ACCOUNT, m); 1003 1004 return (ret); 1005 } 1006 1007 static void *sshpam_ctxt, *sshpam_authok; 1008 extern KbdintDevice sshpam_device; 1009 1010 int 1011 mm_answer_pam_init_ctx(int sock, Buffer *m) 1012 { 1013 debug3("%s", __func__); 1014 if (!options.kbd_interactive_authentication) 1015 fatal("%s: kbd-int authentication not enabled", __func__); 1016 if (sshpam_ctxt != NULL) 1017 fatal("%s: already called", __func__); 1018 sshpam_ctxt = (sshpam_device.init_ctx)(authctxt); 1019 sshpam_authok = NULL; 1020 buffer_clear(m); 1021 if (sshpam_ctxt != NULL) { 1022 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_FREE_CTX, 1); 1023 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_QUERY, 1); 1024 buffer_put_int(m, 1); 1025 } else { 1026 buffer_put_int(m, 0); 1027 } 1028 mm_request_send(sock, MONITOR_ANS_PAM_INIT_CTX, m); 1029 return (0); 1030 } 1031 1032 int 1033 mm_answer_pam_query(int sock, Buffer *m) 1034 { 1035 char *name = NULL, *info = NULL, **prompts = NULL; 1036 u_int i, num = 0, *echo_on = 0; 1037 int ret; 1038 1039 debug3("%s", __func__); 1040 sshpam_authok = NULL; 1041 if (sshpam_ctxt == NULL) 1042 fatal("%s: no context", __func__); 1043 ret = (sshpam_device.query)(sshpam_ctxt, &name, &info, 1044 &num, &prompts, &echo_on); 1045 if (ret == 0 && num == 0) 1046 sshpam_authok = sshpam_ctxt; 1047 if (num > 1 || name == NULL || info == NULL) 1048 fatal("sshpam_device.query failed"); 1049 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_RESPOND, 1); 1050 buffer_clear(m); 1051 buffer_put_int(m, ret); 1052 buffer_put_cstring(m, name); 1053 free(name); 1054 buffer_put_cstring(m, info); 1055 free(info); 1056 buffer_put_int(m, sshpam_get_maxtries_reached()); 1057 buffer_put_int(m, num); 1058 for (i = 0; i < num; ++i) { 1059 buffer_put_cstring(m, prompts[i]); 1060 free(prompts[i]); 1061 buffer_put_int(m, echo_on[i]); 1062 } 1063 free(prompts); 1064 free(echo_on); 1065 auth_method = "keyboard-interactive"; 1066 auth_submethod = "pam"; 1067 mm_request_send(sock, MONITOR_ANS_PAM_QUERY, m); 1068 return (0); 1069 } 1070 1071 int 1072 mm_answer_pam_respond(int sock, Buffer *m) 1073 { 1074 char **resp; 1075 u_int i, num; 1076 int ret; 1077 1078 debug3("%s", __func__); 1079 if (sshpam_ctxt == NULL) 1080 fatal("%s: no context", __func__); 1081 sshpam_authok = NULL; 1082 num = buffer_get_int(m); 1083 if (num > 0) { 1084 resp = xcalloc(num, sizeof(char *)); 1085 for (i = 0; i < num; ++i) 1086 resp[i] = buffer_get_string(m, NULL); 1087 ret = (sshpam_device.respond)(sshpam_ctxt, num, resp); 1088 for (i = 0; i < num; ++i) 1089 free(resp[i]); 1090 free(resp); 1091 } else { 1092 ret = (sshpam_device.respond)(sshpam_ctxt, num, NULL); 1093 } 1094 buffer_clear(m); 1095 buffer_put_int(m, ret); 1096 mm_request_send(sock, MONITOR_ANS_PAM_RESPOND, m); 1097 auth_method = "keyboard-interactive"; 1098 auth_submethod = "pam"; 1099 if (ret == 0) 1100 sshpam_authok = sshpam_ctxt; 1101 return (0); 1102 } 1103 1104 int 1105 mm_answer_pam_free_ctx(int sock, Buffer *m) 1106 { 1107 int r = sshpam_authok != NULL && sshpam_authok == sshpam_ctxt; 1108 1109 debug3("%s", __func__); 1110 if (sshpam_ctxt == NULL) 1111 fatal("%s: no context", __func__); 1112 (sshpam_device.free_ctx)(sshpam_ctxt); 1113 sshpam_ctxt = sshpam_authok = NULL; 1114 buffer_clear(m); 1115 mm_request_send(sock, MONITOR_ANS_PAM_FREE_CTX, m); 1116 /* Allow another attempt */ 1117 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_INIT_CTX, 1); 1118 auth_method = "keyboard-interactive"; 1119 auth_submethod = "pam"; 1120 return r; 1121 } 1122 #endif 1123 1124 int 1125 mm_answer_keyallowed(int sock, Buffer *m) 1126 { 1127 Key *key; 1128 char *cuser, *chost; 1129 u_char *blob; 1130 u_int bloblen, pubkey_auth_attempt; 1131 enum mm_keytype type = 0; 1132 int allowed = 0; 1133 1134 debug3("%s entering", __func__); 1135 1136 type = buffer_get_int(m); 1137 cuser = buffer_get_string(m, NULL); 1138 chost = buffer_get_string(m, NULL); 1139 blob = buffer_get_string(m, &bloblen); 1140 pubkey_auth_attempt = buffer_get_int(m); 1141 1142 key = key_from_blob(blob, bloblen); 1143 1144 debug3("%s: key_from_blob: %p", __func__, key); 1145 1146 if (key != NULL && authctxt->valid) { 1147 /* These should not make it past the privsep child */ 1148 if (key_type_plain(key->type) == KEY_RSA && 1149 (datafellows & SSH_BUG_RSASIGMD5) != 0) 1150 fatal("%s: passed a SSH_BUG_RSASIGMD5 key", __func__); 1151 1152 switch (type) { 1153 case MM_USERKEY: 1154 allowed = options.pubkey_authentication && 1155 !auth2_userkey_already_used(authctxt, key) && 1156 match_pattern_list(sshkey_ssh_name(key), 1157 options.pubkey_key_types, 0) == 1 && 1158 user_key_allowed(authctxt->pw, key, 1159 pubkey_auth_attempt); 1160 pubkey_auth_info(authctxt, key, NULL); 1161 auth_method = "publickey"; 1162 if (options.pubkey_authentication && 1163 (!pubkey_auth_attempt || allowed != 1)) 1164 auth_clear_options(); 1165 break; 1166 case MM_HOSTKEY: 1167 allowed = options.hostbased_authentication && 1168 match_pattern_list(sshkey_ssh_name(key), 1169 options.hostbased_key_types, 0) == 1 && 1170 hostbased_key_allowed(authctxt->pw, 1171 cuser, chost, key); 1172 pubkey_auth_info(authctxt, key, 1173 "client user \"%.100s\", client host \"%.100s\"", 1174 cuser, chost); 1175 auth_method = "hostbased"; 1176 break; 1177 default: 1178 fatal("%s: unknown key type %d", __func__, type); 1179 break; 1180 } 1181 } 1182 1183 debug3("%s: key %p is %s", 1184 __func__, key, allowed ? "allowed" : "not allowed"); 1185 1186 if (key != NULL) 1187 key_free(key); 1188 1189 /* clear temporarily storage (used by verify) */ 1190 monitor_reset_key_state(); 1191 1192 if (allowed) { 1193 /* Save temporarily for comparison in verify */ 1194 key_blob = blob; 1195 key_bloblen = bloblen; 1196 key_blobtype = type; 1197 hostbased_cuser = cuser; 1198 hostbased_chost = chost; 1199 } else { 1200 /* Log failed attempt */ 1201 auth_log(authctxt, 0, 0, auth_method, NULL); 1202 free(blob); 1203 free(cuser); 1204 free(chost); 1205 } 1206 1207 buffer_clear(m); 1208 buffer_put_int(m, allowed); 1209 buffer_put_int(m, forced_command != NULL); 1210 1211 mm_request_send(sock, MONITOR_ANS_KEYALLOWED, m); 1212 1213 return (0); 1214 } 1215 1216 static int 1217 monitor_valid_userblob(u_char *data, u_int datalen) 1218 { 1219 Buffer b; 1220 u_char *p; 1221 char *userstyle, *cp; 1222 u_int len; 1223 int fail = 0; 1224 1225 buffer_init(&b); 1226 buffer_append(&b, data, datalen); 1227 1228 if (datafellows & SSH_OLD_SESSIONID) { 1229 p = buffer_ptr(&b); 1230 len = buffer_len(&b); 1231 if ((session_id2 == NULL) || 1232 (len < session_id2_len) || 1233 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) 1234 fail++; 1235 buffer_consume(&b, session_id2_len); 1236 } else { 1237 p = buffer_get_string(&b, &len); 1238 if ((session_id2 == NULL) || 1239 (len != session_id2_len) || 1240 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) 1241 fail++; 1242 free(p); 1243 } 1244 if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST) 1245 fail++; 1246 cp = buffer_get_cstring(&b, NULL); 1247 xasprintf(&userstyle, "%s%s%s", authctxt->user, 1248 authctxt->style ? ":" : "", 1249 authctxt->style ? authctxt->style : ""); 1250 if (strcmp(userstyle, cp) != 0) { 1251 logit("wrong user name passed to monitor: " 1252 "expected %s != %.100s", userstyle, cp); 1253 fail++; 1254 } 1255 free(userstyle); 1256 free(cp); 1257 buffer_skip_string(&b); 1258 if (datafellows & SSH_BUG_PKAUTH) { 1259 if (!buffer_get_char(&b)) 1260 fail++; 1261 } else { 1262 cp = buffer_get_cstring(&b, NULL); 1263 if (strcmp("publickey", cp) != 0) 1264 fail++; 1265 free(cp); 1266 if (!buffer_get_char(&b)) 1267 fail++; 1268 buffer_skip_string(&b); 1269 } 1270 buffer_skip_string(&b); 1271 if (buffer_len(&b) != 0) 1272 fail++; 1273 buffer_free(&b); 1274 return (fail == 0); 1275 } 1276 1277 static int 1278 monitor_valid_hostbasedblob(u_char *data, u_int datalen, char *cuser, 1279 char *chost) 1280 { 1281 Buffer b; 1282 char *p, *userstyle; 1283 u_int len; 1284 int fail = 0; 1285 1286 buffer_init(&b); 1287 buffer_append(&b, data, datalen); 1288 1289 p = buffer_get_string(&b, &len); 1290 if ((session_id2 == NULL) || 1291 (len != session_id2_len) || 1292 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) 1293 fail++; 1294 free(p); 1295 1296 if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST) 1297 fail++; 1298 p = buffer_get_cstring(&b, NULL); 1299 xasprintf(&userstyle, "%s%s%s", authctxt->user, 1300 authctxt->style ? ":" : "", 1301 authctxt->style ? authctxt->style : ""); 1302 if (strcmp(userstyle, p) != 0) { 1303 logit("wrong user name passed to monitor: expected %s != %.100s", 1304 userstyle, p); 1305 fail++; 1306 } 1307 free(userstyle); 1308 free(p); 1309 buffer_skip_string(&b); /* service */ 1310 p = buffer_get_cstring(&b, NULL); 1311 if (strcmp(p, "hostbased") != 0) 1312 fail++; 1313 free(p); 1314 buffer_skip_string(&b); /* pkalg */ 1315 buffer_skip_string(&b); /* pkblob */ 1316 1317 /* verify client host, strip trailing dot if necessary */ 1318 p = buffer_get_string(&b, NULL); 1319 if (((len = strlen(p)) > 0) && p[len - 1] == '.') 1320 p[len - 1] = '\0'; 1321 if (strcmp(p, chost) != 0) 1322 fail++; 1323 free(p); 1324 1325 /* verify client user */ 1326 p = buffer_get_string(&b, NULL); 1327 if (strcmp(p, cuser) != 0) 1328 fail++; 1329 free(p); 1330 1331 if (buffer_len(&b) != 0) 1332 fail++; 1333 buffer_free(&b); 1334 return (fail == 0); 1335 } 1336 1337 int 1338 mm_answer_keyverify(int sock, Buffer *m) 1339 { 1340 Key *key; 1341 u_char *signature, *data, *blob; 1342 u_int signaturelen, datalen, bloblen; 1343 int verified = 0; 1344 int valid_data = 0; 1345 1346 blob = buffer_get_string(m, &bloblen); 1347 signature = buffer_get_string(m, &signaturelen); 1348 data = buffer_get_string(m, &datalen); 1349 1350 if (hostbased_cuser == NULL || hostbased_chost == NULL || 1351 !monitor_allowed_key(blob, bloblen)) 1352 fatal("%s: bad key, not previously allowed", __func__); 1353 1354 key = key_from_blob(blob, bloblen); 1355 if (key == NULL) 1356 fatal("%s: bad public key blob", __func__); 1357 1358 switch (key_blobtype) { 1359 case MM_USERKEY: 1360 valid_data = monitor_valid_userblob(data, datalen); 1361 break; 1362 case MM_HOSTKEY: 1363 valid_data = monitor_valid_hostbasedblob(data, datalen, 1364 hostbased_cuser, hostbased_chost); 1365 break; 1366 default: 1367 valid_data = 0; 1368 break; 1369 } 1370 if (!valid_data) 1371 fatal("%s: bad signature data blob", __func__); 1372 1373 verified = key_verify(key, signature, signaturelen, data, datalen); 1374 debug3("%s: key %p signature %s", 1375 __func__, key, (verified == 1) ? "verified" : "unverified"); 1376 1377 /* If auth was successful then record key to ensure it isn't reused */ 1378 if (verified == 1 && key_blobtype == MM_USERKEY) 1379 auth2_record_userkey(authctxt, key); 1380 else 1381 key_free(key); 1382 1383 free(blob); 1384 free(signature); 1385 free(data); 1386 1387 auth_method = key_blobtype == MM_USERKEY ? "publickey" : "hostbased"; 1388 1389 monitor_reset_key_state(); 1390 1391 buffer_clear(m); 1392 buffer_put_int(m, verified); 1393 mm_request_send(sock, MONITOR_ANS_KEYVERIFY, m); 1394 1395 return (verified == 1); 1396 } 1397 1398 static void 1399 mm_record_login(Session *s, struct passwd *pw) 1400 { 1401 struct ssh *ssh = active_state; /* XXX */ 1402 socklen_t fromlen; 1403 struct sockaddr_storage from; 1404 1405 /* 1406 * Get IP address of client. If the connection is not a socket, let 1407 * the address be 0.0.0.0. 1408 */ 1409 memset(&from, 0, sizeof(from)); 1410 fromlen = sizeof(from); 1411 if (packet_connection_is_on_socket()) { 1412 if (getpeername(packet_get_connection_in(), 1413 (struct sockaddr *)&from, &fromlen) < 0) { 1414 debug("getpeername: %.100s", strerror(errno)); 1415 cleanup_exit(255); 1416 } 1417 } 1418 /* Record that there was a login on that tty from the remote host. */ 1419 record_login(s->pid, s->tty, pw->pw_name, pw->pw_uid, 1420 session_get_remote_name_or_ip(ssh, utmp_len, options.use_dns), 1421 (struct sockaddr *)&from, fromlen); 1422 } 1423 1424 static void 1425 mm_session_close(Session *s) 1426 { 1427 debug3("%s: session %d pid %ld", __func__, s->self, (long)s->pid); 1428 if (s->ttyfd != -1) { 1429 debug3("%s: tty %s ptyfd %d", __func__, s->tty, s->ptyfd); 1430 session_pty_cleanup2(s); 1431 } 1432 session_unused(s->self); 1433 } 1434 1435 int 1436 mm_answer_pty(int sock, Buffer *m) 1437 { 1438 extern struct monitor *pmonitor; 1439 Session *s; 1440 int res, fd0; 1441 1442 debug3("%s entering", __func__); 1443 1444 buffer_clear(m); 1445 s = session_new(); 1446 if (s == NULL) 1447 goto error; 1448 s->authctxt = authctxt; 1449 s->pw = authctxt->pw; 1450 s->pid = pmonitor->m_pid; 1451 res = pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty)); 1452 if (res == 0) 1453 goto error; 1454 pty_setowner(authctxt->pw, s->tty); 1455 1456 buffer_put_int(m, 1); 1457 buffer_put_cstring(m, s->tty); 1458 1459 /* We need to trick ttyslot */ 1460 if (dup2(s->ttyfd, 0) == -1) 1461 fatal("%s: dup2", __func__); 1462 1463 mm_record_login(s, authctxt->pw); 1464 1465 /* Now we can close the file descriptor again */ 1466 close(0); 1467 1468 /* send messages generated by record_login */ 1469 buffer_put_string(m, buffer_ptr(&loginmsg), buffer_len(&loginmsg)); 1470 buffer_clear(&loginmsg); 1471 1472 mm_request_send(sock, MONITOR_ANS_PTY, m); 1473 1474 if (mm_send_fd(sock, s->ptyfd) == -1 || 1475 mm_send_fd(sock, s->ttyfd) == -1) 1476 fatal("%s: send fds failed", __func__); 1477 1478 /* make sure nothing uses fd 0 */ 1479 if ((fd0 = open(_PATH_DEVNULL, O_RDONLY)) < 0) 1480 fatal("%s: open(/dev/null): %s", __func__, strerror(errno)); 1481 if (fd0 != 0) 1482 error("%s: fd0 %d != 0", __func__, fd0); 1483 1484 /* slave is not needed */ 1485 close(s->ttyfd); 1486 s->ttyfd = s->ptyfd; 1487 /* no need to dup() because nobody closes ptyfd */ 1488 s->ptymaster = s->ptyfd; 1489 1490 debug3("%s: tty %s ptyfd %d", __func__, s->tty, s->ttyfd); 1491 1492 return (0); 1493 1494 error: 1495 if (s != NULL) 1496 mm_session_close(s); 1497 buffer_put_int(m, 0); 1498 mm_request_send(sock, MONITOR_ANS_PTY, m); 1499 return (0); 1500 } 1501 1502 int 1503 mm_answer_pty_cleanup(int sock, Buffer *m) 1504 { 1505 Session *s; 1506 char *tty; 1507 1508 debug3("%s entering", __func__); 1509 1510 tty = buffer_get_string(m, NULL); 1511 if ((s = session_by_tty(tty)) != NULL) 1512 mm_session_close(s); 1513 buffer_clear(m); 1514 free(tty); 1515 return (0); 1516 } 1517 1518 int 1519 mm_answer_term(int sock, Buffer *req) 1520 { 1521 extern struct monitor *pmonitor; 1522 int res, status; 1523 1524 debug3("%s: tearing down sessions", __func__); 1525 1526 /* The child is terminating */ 1527 session_destroy_all(&mm_session_close); 1528 1529 #ifdef USE_PAM 1530 if (options.use_pam) 1531 sshpam_cleanup(); 1532 #endif 1533 1534 while (waitpid(pmonitor->m_pid, &status, 0) == -1) 1535 if (errno != EINTR) 1536 exit(1); 1537 1538 res = WIFEXITED(status) ? WEXITSTATUS(status) : 1; 1539 1540 /* Terminate process */ 1541 exit(res); 1542 } 1543 1544 #ifdef SSH_AUDIT_EVENTS 1545 /* Report that an audit event occurred */ 1546 int 1547 mm_answer_audit_event(int socket, Buffer *m) 1548 { 1549 ssh_audit_event_t event; 1550 1551 debug3("%s entering", __func__); 1552 1553 event = buffer_get_int(m); 1554 switch(event) { 1555 case SSH_AUTH_FAIL_PUBKEY: 1556 case SSH_AUTH_FAIL_HOSTBASED: 1557 case SSH_AUTH_FAIL_GSSAPI: 1558 case SSH_LOGIN_EXCEED_MAXTRIES: 1559 case SSH_LOGIN_ROOT_DENIED: 1560 case SSH_CONNECTION_CLOSE: 1561 case SSH_INVALID_USER: 1562 audit_event(event); 1563 break; 1564 default: 1565 fatal("Audit event type %d not permitted", event); 1566 } 1567 1568 return (0); 1569 } 1570 1571 int 1572 mm_answer_audit_command(int socket, Buffer *m) 1573 { 1574 u_int len; 1575 char *cmd; 1576 1577 debug3("%s entering", __func__); 1578 cmd = buffer_get_string(m, &len); 1579 /* sanity check command, if so how? */ 1580 audit_run_command(cmd); 1581 free(cmd); 1582 return (0); 1583 } 1584 #endif /* SSH_AUDIT_EVENTS */ 1585 1586 void 1587 monitor_apply_keystate(struct monitor *pmonitor) 1588 { 1589 struct ssh *ssh = active_state; /* XXX */ 1590 struct kex *kex; 1591 int r; 1592 1593 debug3("%s: packet_set_state", __func__); 1594 if ((r = ssh_packet_set_state(ssh, child_state)) != 0) 1595 fatal("%s: packet_set_state: %s", __func__, ssh_err(r)); 1596 sshbuf_free(child_state); 1597 child_state = NULL; 1598 1599 if ((kex = ssh->kex) != NULL) { 1600 /* XXX set callbacks */ 1601 #ifdef WITH_OPENSSL 1602 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 1603 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 1604 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server; 1605 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server; 1606 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server; 1607 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 1608 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 1609 # ifdef OPENSSL_HAS_ECC 1610 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 1611 # endif 1612 #endif /* WITH_OPENSSL */ 1613 kex->kex[KEX_C25519_SHA256] = kexc25519_server; 1614 kex->load_host_public_key=&get_hostkey_public_by_type; 1615 kex->load_host_private_key=&get_hostkey_private_by_type; 1616 kex->host_key_index=&get_hostkey_index; 1617 kex->sign = sshd_hostkey_sign; 1618 } 1619 } 1620 1621 /* This function requries careful sanity checking */ 1622 1623 void 1624 mm_get_keystate(struct monitor *pmonitor) 1625 { 1626 debug3("%s: Waiting for new keys", __func__); 1627 1628 if ((child_state = sshbuf_new()) == NULL) 1629 fatal("%s: sshbuf_new failed", __func__); 1630 mm_request_receive_expect(pmonitor->m_sendfd, MONITOR_REQ_KEYEXPORT, 1631 child_state); 1632 debug3("%s: GOT new keys", __func__); 1633 } 1634 1635 1636 /* XXX */ 1637 1638 #define FD_CLOSEONEXEC(x) do { \ 1639 if (fcntl(x, F_SETFD, FD_CLOEXEC) == -1) \ 1640 fatal("fcntl(%d, F_SETFD)", x); \ 1641 } while (0) 1642 1643 static void 1644 monitor_openfds(struct monitor *mon, int do_logfds) 1645 { 1646 int pair[2]; 1647 1648 if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) 1649 fatal("%s: socketpair: %s", __func__, strerror(errno)); 1650 FD_CLOSEONEXEC(pair[0]); 1651 FD_CLOSEONEXEC(pair[1]); 1652 mon->m_recvfd = pair[0]; 1653 mon->m_sendfd = pair[1]; 1654 1655 if (do_logfds) { 1656 if (pipe(pair) == -1) 1657 fatal("%s: pipe: %s", __func__, strerror(errno)); 1658 FD_CLOSEONEXEC(pair[0]); 1659 FD_CLOSEONEXEC(pair[1]); 1660 mon->m_log_recvfd = pair[0]; 1661 mon->m_log_sendfd = pair[1]; 1662 } else 1663 mon->m_log_recvfd = mon->m_log_sendfd = -1; 1664 } 1665 1666 #define MM_MEMSIZE 65536 1667 1668 struct monitor * 1669 monitor_init(void) 1670 { 1671 struct monitor *mon; 1672 1673 mon = xcalloc(1, sizeof(*mon)); 1674 monitor_openfds(mon, 1); 1675 1676 return mon; 1677 } 1678 1679 void 1680 monitor_reinit(struct monitor *mon) 1681 { 1682 monitor_openfds(mon, 0); 1683 } 1684 1685 #ifdef GSSAPI 1686 int 1687 mm_answer_gss_setup_ctx(int sock, Buffer *m) 1688 { 1689 gss_OID_desc goid; 1690 OM_uint32 major; 1691 u_int len; 1692 1693 if (!options.gss_authentication) 1694 fatal("%s: GSSAPI authentication not enabled", __func__); 1695 1696 goid.elements = buffer_get_string(m, &len); 1697 goid.length = len; 1698 1699 major = ssh_gssapi_server_ctx(&gsscontext, &goid); 1700 1701 free(goid.elements); 1702 1703 buffer_clear(m); 1704 buffer_put_int(m, major); 1705 1706 mm_request_send(sock, MONITOR_ANS_GSSSETUP, m); 1707 1708 /* Now we have a context, enable the step */ 1709 monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 1); 1710 1711 return (0); 1712 } 1713 1714 int 1715 mm_answer_gss_accept_ctx(int sock, Buffer *m) 1716 { 1717 gss_buffer_desc in; 1718 gss_buffer_desc out = GSS_C_EMPTY_BUFFER; 1719 OM_uint32 major, minor; 1720 OM_uint32 flags = 0; /* GSI needs this */ 1721 u_int len; 1722 1723 if (!options.gss_authentication) 1724 fatal("%s: GSSAPI authentication not enabled", __func__); 1725 1726 in.value = buffer_get_string(m, &len); 1727 in.length = len; 1728 major = ssh_gssapi_accept_ctx(gsscontext, &in, &out, &flags); 1729 free(in.value); 1730 1731 buffer_clear(m); 1732 buffer_put_int(m, major); 1733 buffer_put_string(m, out.value, out.length); 1734 buffer_put_int(m, flags); 1735 mm_request_send(sock, MONITOR_ANS_GSSSTEP, m); 1736 1737 gss_release_buffer(&minor, &out); 1738 1739 if (major == GSS_S_COMPLETE) { 1740 monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 0); 1741 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1); 1742 monitor_permit(mon_dispatch, MONITOR_REQ_GSSCHECKMIC, 1); 1743 } 1744 return (0); 1745 } 1746 1747 int 1748 mm_answer_gss_checkmic(int sock, Buffer *m) 1749 { 1750 gss_buffer_desc gssbuf, mic; 1751 OM_uint32 ret; 1752 u_int len; 1753 1754 if (!options.gss_authentication) 1755 fatal("%s: GSSAPI authentication not enabled", __func__); 1756 1757 gssbuf.value = buffer_get_string(m, &len); 1758 gssbuf.length = len; 1759 mic.value = buffer_get_string(m, &len); 1760 mic.length = len; 1761 1762 ret = ssh_gssapi_checkmic(gsscontext, &gssbuf, &mic); 1763 1764 free(gssbuf.value); 1765 free(mic.value); 1766 1767 buffer_clear(m); 1768 buffer_put_int(m, ret); 1769 1770 mm_request_send(sock, MONITOR_ANS_GSSCHECKMIC, m); 1771 1772 if (!GSS_ERROR(ret)) 1773 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1); 1774 1775 return (0); 1776 } 1777 1778 int 1779 mm_answer_gss_userok(int sock, Buffer *m) 1780 { 1781 int authenticated; 1782 1783 if (!options.gss_authentication) 1784 fatal("%s: GSSAPI authentication not enabled", __func__); 1785 1786 authenticated = authctxt->valid && ssh_gssapi_userok(authctxt->user); 1787 1788 buffer_clear(m); 1789 buffer_put_int(m, authenticated); 1790 1791 debug3("%s: sending result %d", __func__, authenticated); 1792 mm_request_send(sock, MONITOR_ANS_GSSUSEROK, m); 1793 1794 auth_method = "gssapi-with-mic"; 1795 1796 /* Monitor loop will terminate if authenticated */ 1797 return (authenticated); 1798 } 1799 #endif /* GSSAPI */ 1800
