1 /* $OpenBSD: monitor.c,v 1.180 2018/03/03 03:15:51 djm 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 "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 extern struct sshauthopt *auth_opts; /* XXX move to permanent ssh->authctxt? */ 120 121 /* State exported from the child */ 122 static struct sshbuf *child_state; 123 124 /* Functions on the monitor that answer unprivileged requests */ 125 126 int mm_answer_moduli(int, Buffer *); 127 int mm_answer_sign(int, Buffer *); 128 int mm_answer_pwnamallow(int, Buffer *); 129 int mm_answer_auth2_read_banner(int, Buffer *); 130 int mm_answer_authserv(int, Buffer *); 131 int mm_answer_authpassword(int, Buffer *); 132 int mm_answer_bsdauthquery(int, Buffer *); 133 int mm_answer_bsdauthrespond(int, Buffer *); 134 int mm_answer_skeyquery(int, Buffer *); 135 int mm_answer_skeyrespond(int, Buffer *); 136 int mm_answer_keyallowed(int, Buffer *); 137 int mm_answer_keyverify(int, Buffer *); 138 int mm_answer_pty(int, Buffer *); 139 int mm_answer_pty_cleanup(int, Buffer *); 140 int mm_answer_term(int, Buffer *); 141 int mm_answer_rsa_keyallowed(int, Buffer *); 142 int mm_answer_rsa_challenge(int, Buffer *); 143 int mm_answer_rsa_response(int, Buffer *); 144 int mm_answer_sesskey(int, Buffer *); 145 int mm_answer_sessid(int, Buffer *); 146 147 #ifdef USE_PAM 148 int mm_answer_pam_start(int, Buffer *); 149 int mm_answer_pam_account(int, Buffer *); 150 int mm_answer_pam_init_ctx(int, Buffer *); 151 int mm_answer_pam_query(int, Buffer *); 152 int mm_answer_pam_respond(int, Buffer *); 153 int mm_answer_pam_free_ctx(int, Buffer *); 154 #endif 155 156 #ifdef GSSAPI 157 int mm_answer_gss_setup_ctx(int, Buffer *); 158 int mm_answer_gss_accept_ctx(int, Buffer *); 159 int mm_answer_gss_userok(int, Buffer *); 160 int mm_answer_gss_checkmic(int, Buffer *); 161 #endif 162 163 #ifdef SSH_AUDIT_EVENTS 164 int mm_answer_audit_event(int, Buffer *); 165 int mm_answer_audit_command(int, Buffer *); 166 #endif 167 168 static int monitor_read_log(struct monitor *); 169 170 static Authctxt *authctxt; 171 172 /* local state for key verify */ 173 static u_char *key_blob = NULL; 174 static u_int key_bloblen = 0; 175 static int key_blobtype = MM_NOKEY; 176 static struct sshauthopt *key_opts = NULL; 177 static char *hostbased_cuser = NULL; 178 static char *hostbased_chost = NULL; 179 static char *auth_method = "unknown"; 180 static char *auth_submethod = NULL; 181 static u_int session_id2_len = 0; 182 static u_char *session_id2 = NULL; 183 static pid_t monitor_child_pid; 184 185 struct mon_table { 186 enum monitor_reqtype type; 187 int flags; 188 int (*f)(int, Buffer *); 189 }; 190 191 #define MON_ISAUTH 0x0004 /* Required for Authentication */ 192 #define MON_AUTHDECIDE 0x0008 /* Decides Authentication */ 193 #define MON_ONCE 0x0010 /* Disable after calling */ 194 #define MON_ALOG 0x0020 /* Log auth attempt without authenticating */ 195 196 #define MON_AUTH (MON_ISAUTH|MON_AUTHDECIDE) 197 198 #define MON_PERMIT 0x1000 /* Request is permitted */ 199 200 struct mon_table mon_dispatch_proto20[] = { 201 #ifdef WITH_OPENSSL 202 {MONITOR_REQ_MODULI, MON_ONCE, mm_answer_moduli}, 203 #endif 204 {MONITOR_REQ_SIGN, MON_ONCE, mm_answer_sign}, 205 {MONITOR_REQ_PWNAM, MON_ONCE, mm_answer_pwnamallow}, 206 {MONITOR_REQ_AUTHSERV, MON_ONCE, mm_answer_authserv}, 207 {MONITOR_REQ_AUTH2_READ_BANNER, MON_ONCE, mm_answer_auth2_read_banner}, 208 {MONITOR_REQ_AUTHPASSWORD, MON_AUTH, mm_answer_authpassword}, 209 #ifdef USE_PAM 210 {MONITOR_REQ_PAM_START, MON_ONCE, mm_answer_pam_start}, 211 {MONITOR_REQ_PAM_ACCOUNT, 0, mm_answer_pam_account}, 212 {MONITOR_REQ_PAM_INIT_CTX, MON_ONCE, mm_answer_pam_init_ctx}, 213 {MONITOR_REQ_PAM_QUERY, 0, mm_answer_pam_query}, 214 {MONITOR_REQ_PAM_RESPOND, MON_ONCE, mm_answer_pam_respond}, 215 {MONITOR_REQ_PAM_FREE_CTX, MON_ONCE|MON_AUTHDECIDE, mm_answer_pam_free_ctx}, 216 #endif 217 #ifdef SSH_AUDIT_EVENTS 218 {MONITOR_REQ_AUDIT_EVENT, MON_PERMIT, mm_answer_audit_event}, 219 #endif 220 #ifdef BSD_AUTH 221 {MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery}, 222 {MONITOR_REQ_BSDAUTHRESPOND, MON_AUTH, mm_answer_bsdauthrespond}, 223 #endif 224 #ifdef SKEY 225 {MONITOR_REQ_SKEYQUERY, MON_ISAUTH, mm_answer_skeyquery}, 226 {MONITOR_REQ_SKEYRESPOND, MON_AUTH, mm_answer_skeyrespond}, 227 #endif 228 {MONITOR_REQ_KEYALLOWED, MON_ISAUTH, mm_answer_keyallowed}, 229 {MONITOR_REQ_KEYVERIFY, MON_AUTH, mm_answer_keyverify}, 230 #ifdef GSSAPI 231 {MONITOR_REQ_GSSSETUP, MON_ISAUTH, mm_answer_gss_setup_ctx}, 232 {MONITOR_REQ_GSSSTEP, 0, mm_answer_gss_accept_ctx}, 233 {MONITOR_REQ_GSSUSEROK, MON_ONCE|MON_AUTHDECIDE, mm_answer_gss_userok}, 234 {MONITOR_REQ_GSSCHECKMIC, MON_ONCE, mm_answer_gss_checkmic}, 235 #endif 236 {0, 0, NULL} 237 }; 238 239 struct mon_table mon_dispatch_postauth20[] = { 240 #ifdef WITH_OPENSSL 241 {MONITOR_REQ_MODULI, 0, mm_answer_moduli}, 242 #endif 243 {MONITOR_REQ_SIGN, 0, mm_answer_sign}, 244 {MONITOR_REQ_PTY, 0, mm_answer_pty}, 245 {MONITOR_REQ_PTYCLEANUP, 0, mm_answer_pty_cleanup}, 246 {MONITOR_REQ_TERM, 0, mm_answer_term}, 247 #ifdef SSH_AUDIT_EVENTS 248 {MONITOR_REQ_AUDIT_EVENT, MON_PERMIT, mm_answer_audit_event}, 249 {MONITOR_REQ_AUDIT_COMMAND, MON_PERMIT, mm_answer_audit_command}, 250 #endif 251 {0, 0, NULL} 252 }; 253 254 struct mon_table *mon_dispatch; 255 256 /* Specifies if a certain message is allowed at the moment */ 257 static void 258 monitor_permit(struct mon_table *ent, enum monitor_reqtype type, int permit) 259 { 260 while (ent->f != NULL) { 261 if (ent->type == type) { 262 ent->flags &= ~MON_PERMIT; 263 ent->flags |= permit ? MON_PERMIT : 0; 264 return; 265 } 266 ent++; 267 } 268 } 269 270 static void 271 monitor_permit_authentications(int permit) 272 { 273 struct mon_table *ent = mon_dispatch; 274 275 while (ent->f != NULL) { 276 if (ent->flags & MON_AUTH) { 277 ent->flags &= ~MON_PERMIT; 278 ent->flags |= permit ? MON_PERMIT : 0; 279 } 280 ent++; 281 } 282 } 283 284 void 285 monitor_child_preauth(Authctxt *_authctxt, struct monitor *pmonitor) 286 { 287 struct ssh *ssh = active_state; /* XXX */ 288 struct mon_table *ent; 289 int authenticated = 0, partial = 0; 290 291 debug3("preauth child monitor started"); 292 293 if (pmonitor->m_recvfd >= 0) 294 close(pmonitor->m_recvfd); 295 if (pmonitor->m_log_sendfd >= 0) 296 close(pmonitor->m_log_sendfd); 297 pmonitor->m_log_sendfd = pmonitor->m_recvfd = -1; 298 299 authctxt = _authctxt; 300 memset(authctxt, 0, sizeof(*authctxt)); 301 ssh->authctxt = authctxt; 302 303 authctxt->loginmsg = &loginmsg; 304 305 mon_dispatch = mon_dispatch_proto20; 306 /* Permit requests for moduli and signatures */ 307 monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); 308 monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); 309 310 /* The first few requests do not require asynchronous access */ 311 while (!authenticated) { 312 partial = 0; 313 auth_method = "unknown"; 314 auth_submethod = NULL; 315 auth2_authctxt_reset_info(authctxt); 316 317 authenticated = (monitor_read(pmonitor, mon_dispatch, &ent) == 1); 318 319 /* Special handling for multiple required authentications */ 320 if (options.num_auth_methods != 0) { 321 if (authenticated && 322 !auth2_update_methods_lists(authctxt, 323 auth_method, auth_submethod)) { 324 debug3("%s: method %s: partial", __func__, 325 auth_method); 326 authenticated = 0; 327 partial = 1; 328 } 329 } 330 331 if (authenticated) { 332 if (!(ent->flags & MON_AUTHDECIDE)) 333 fatal("%s: unexpected authentication from %d", 334 __func__, ent->type); 335 if (authctxt->pw->pw_uid == 0 && 336 !auth_root_allowed(ssh, auth_method)) 337 authenticated = 0; 338 #ifdef USE_PAM 339 /* PAM needs to perform account checks after auth */ 340 if (options.use_pam && authenticated) { 341 Buffer m; 342 343 buffer_init(&m); 344 mm_request_receive_expect(pmonitor->m_sendfd, 345 MONITOR_REQ_PAM_ACCOUNT, &m); 346 authenticated = mm_answer_pam_account(pmonitor->m_sendfd, &m); 347 buffer_free(&m); 348 } 349 #endif 350 } 351 if (ent->flags & (MON_AUTHDECIDE|MON_ALOG)) { 352 auth_log(authctxt, authenticated, partial, 353 auth_method, auth_submethod); 354 if (!partial && !authenticated) 355 authctxt->failures++; 356 if (authenticated || partial) { 357 auth2_update_session_info(authctxt, 358 auth_method, auth_submethod); 359 } 360 } 361 } 362 363 if (!authctxt->valid) 364 fatal("%s: authenticated invalid user", __func__); 365 if (strcmp(auth_method, "unknown") == 0) 366 fatal("%s: authentication method name unknown", __func__); 367 368 debug("%s: %s has been authenticated by privileged process", 369 __func__, authctxt->user); 370 ssh->authctxt = NULL; 371 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 372 373 mm_get_keystate(pmonitor); 374 375 /* Drain any buffered messages from the child */ 376 while (pmonitor->m_log_recvfd != -1 && monitor_read_log(pmonitor) == 0) 377 ; 378 379 if (pmonitor->m_recvfd >= 0) 380 close(pmonitor->m_recvfd); 381 if (pmonitor->m_log_sendfd >= 0) 382 close(pmonitor->m_log_sendfd); 383 pmonitor->m_sendfd = pmonitor->m_log_recvfd = -1; 384 } 385 386 static void 387 monitor_set_child_handler(pid_t pid) 388 { 389 monitor_child_pid = pid; 390 } 391 392 static void 393 monitor_child_handler(int sig) 394 { 395 kill(monitor_child_pid, sig); 396 } 397 398 void 399 monitor_child_postauth(struct monitor *pmonitor) 400 { 401 close(pmonitor->m_recvfd); 402 pmonitor->m_recvfd = -1; 403 404 monitor_set_child_handler(pmonitor->m_pid); 405 signal(SIGHUP, &monitor_child_handler); 406 signal(SIGTERM, &monitor_child_handler); 407 signal(SIGINT, &monitor_child_handler); 408 #ifdef SIGXFSZ 409 signal(SIGXFSZ, SIG_IGN); 410 #endif 411 412 mon_dispatch = mon_dispatch_postauth20; 413 414 /* Permit requests for moduli and signatures */ 415 monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); 416 monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); 417 monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1); 418 419 if (auth_opts->permit_pty_flag) { 420 monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1); 421 monitor_permit(mon_dispatch, MONITOR_REQ_PTYCLEANUP, 1); 422 } 423 424 for (;;) 425 monitor_read(pmonitor, mon_dispatch, NULL); 426 } 427 428 static int 429 monitor_read_log(struct monitor *pmonitor) 430 { 431 Buffer logmsg; 432 u_int len, level; 433 char *msg; 434 435 buffer_init(&logmsg); 436 437 /* Read length */ 438 buffer_append_space(&logmsg, 4); 439 if (atomicio(read, pmonitor->m_log_recvfd, 440 buffer_ptr(&logmsg), buffer_len(&logmsg)) != buffer_len(&logmsg)) { 441 if (errno == EPIPE) { 442 buffer_free(&logmsg); 443 debug("%s: child log fd closed", __func__); 444 close(pmonitor->m_log_recvfd); 445 pmonitor->m_log_recvfd = -1; 446 return -1; 447 } 448 fatal("%s: log fd read: %s", __func__, strerror(errno)); 449 } 450 len = buffer_get_int(&logmsg); 451 if (len <= 4 || len > 8192) 452 fatal("%s: invalid log message length %u", __func__, len); 453 454 /* Read severity, message */ 455 buffer_clear(&logmsg); 456 buffer_append_space(&logmsg, len); 457 if (atomicio(read, pmonitor->m_log_recvfd, 458 buffer_ptr(&logmsg), buffer_len(&logmsg)) != buffer_len(&logmsg)) 459 fatal("%s: log fd read: %s", __func__, strerror(errno)); 460 461 /* Log it */ 462 level = buffer_get_int(&logmsg); 463 msg = buffer_get_string(&logmsg, NULL); 464 if (log_level_name(level) == NULL) 465 fatal("%s: invalid log level %u (corrupted message?)", 466 __func__, level); 467 do_log2(level, "%s [preauth]", msg); 468 469 buffer_free(&logmsg); 470 free(msg); 471 472 return 0; 473 } 474 475 int 476 monitor_read(struct monitor *pmonitor, struct mon_table *ent, 477 struct mon_table **pent) 478 { 479 Buffer m; 480 int ret; 481 u_char type; 482 struct pollfd pfd[2]; 483 484 for (;;) { 485 memset(&pfd, 0, sizeof(pfd)); 486 pfd[0].fd = pmonitor->m_sendfd; 487 pfd[0].events = POLLIN; 488 pfd[1].fd = pmonitor->m_log_recvfd; 489 pfd[1].events = pfd[1].fd == -1 ? 0 : POLLIN; 490 if (poll(pfd, pfd[1].fd == -1 ? 1 : 2, -1) == -1) { 491 if (errno == EINTR || errno == EAGAIN) 492 continue; 493 fatal("%s: poll: %s", __func__, strerror(errno)); 494 } 495 if (pfd[1].revents) { 496 /* 497 * Drain all log messages before processing next 498 * monitor request. 499 */ 500 monitor_read_log(pmonitor); 501 continue; 502 } 503 if (pfd[0].revents) 504 break; /* Continues below */ 505 } 506 507 buffer_init(&m); 508 509 mm_request_receive(pmonitor->m_sendfd, &m); 510 type = buffer_get_char(&m); 511 512 debug3("%s: checking request %d", __func__, type); 513 514 while (ent->f != NULL) { 515 if (ent->type == type) 516 break; 517 ent++; 518 } 519 520 if (ent->f != NULL) { 521 if (!(ent->flags & MON_PERMIT)) 522 fatal("%s: unpermitted request %d", __func__, 523 type); 524 ret = (*ent->f)(pmonitor->m_sendfd, &m); 525 buffer_free(&m); 526 527 /* The child may use this request only once, disable it */ 528 if (ent->flags & MON_ONCE) { 529 debug2("%s: %d used once, disabling now", __func__, 530 type); 531 ent->flags &= ~MON_PERMIT; 532 } 533 534 if (pent != NULL) 535 *pent = ent; 536 537 return ret; 538 } 539 540 fatal("%s: unsupported request: %d", __func__, type); 541 542 /* NOTREACHED */ 543 return (-1); 544 } 545 546 /* allowed key state */ 547 static int 548 monitor_allowed_key(u_char *blob, u_int bloblen) 549 { 550 /* make sure key is allowed */ 551 if (key_blob == NULL || key_bloblen != bloblen || 552 timingsafe_bcmp(key_blob, blob, key_bloblen)) 553 return (0); 554 return (1); 555 } 556 557 static void 558 monitor_reset_key_state(void) 559 { 560 /* reset state */ 561 free(key_blob); 562 free(hostbased_cuser); 563 free(hostbased_chost); 564 sshauthopt_free(key_opts); 565 key_blob = NULL; 566 key_bloblen = 0; 567 key_blobtype = MM_NOKEY; 568 key_opts = NULL; 569 hostbased_cuser = NULL; 570 hostbased_chost = NULL; 571 } 572 573 #ifdef WITH_OPENSSL 574 int 575 mm_answer_moduli(int sock, Buffer *m) 576 { 577 DH *dh; 578 int min, want, max; 579 580 min = buffer_get_int(m); 581 want = buffer_get_int(m); 582 max = buffer_get_int(m); 583 584 debug3("%s: got parameters: %d %d %d", 585 __func__, min, want, max); 586 /* We need to check here, too, in case the child got corrupted */ 587 if (max < min || want < min || max < want) 588 fatal("%s: bad parameters: %d %d %d", 589 __func__, min, want, max); 590 591 buffer_clear(m); 592 593 dh = choose_dh(min, want, max); 594 if (dh == NULL) { 595 buffer_put_char(m, 0); 596 return (0); 597 } else { 598 /* Send first bignum */ 599 buffer_put_char(m, 1); 600 buffer_put_bignum2(m, dh->p); 601 buffer_put_bignum2(m, dh->g); 602 603 DH_free(dh); 604 } 605 mm_request_send(sock, MONITOR_ANS_MODULI, m); 606 return (0); 607 } 608 #endif 609 610 int 611 mm_answer_sign(int sock, Buffer *m) 612 { 613 struct ssh *ssh = active_state; /* XXX */ 614 extern int auth_sock; /* XXX move to state struct? */ 615 struct sshkey *key; 616 struct sshbuf *sigbuf = NULL; 617 u_char *p = NULL, *signature = NULL; 618 char *alg = NULL; 619 size_t datlen, siglen, alglen; 620 int r, is_proof = 0; 621 u_int keyid; 622 const char proof_req[] = "hostkeys-prove-00@openssh.com"; 623 624 debug3("%s", __func__); 625 626 if ((r = sshbuf_get_u32(m, &keyid)) != 0 || 627 (r = sshbuf_get_string(m, &p, &datlen)) != 0 || 628 (r = sshbuf_get_cstring(m, &alg, &alglen)) != 0) 629 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 630 if (keyid > INT_MAX) 631 fatal("%s: invalid key ID", __func__); 632 633 /* 634 * Supported KEX types use SHA1 (20 bytes), SHA256 (32 bytes), 635 * SHA384 (48 bytes) and SHA512 (64 bytes). 636 * 637 * Otherwise, verify the signature request is for a hostkey 638 * proof. 639 * 640 * XXX perform similar check for KEX signature requests too? 641 * it's not trivial, since what is signed is the hash, rather 642 * than the full kex structure... 643 */ 644 if (datlen != 20 && datlen != 32 && datlen != 48 && datlen != 64) { 645 /* 646 * Construct expected hostkey proof and compare it to what 647 * the client sent us. 648 */ 649 if (session_id2_len == 0) /* hostkeys is never first */ 650 fatal("%s: bad data length: %zu", __func__, datlen); 651 if ((key = get_hostkey_public_by_index(keyid, ssh)) == NULL) 652 fatal("%s: no hostkey for index %d", __func__, keyid); 653 if ((sigbuf = sshbuf_new()) == NULL) 654 fatal("%s: sshbuf_new", __func__); 655 if ((r = sshbuf_put_cstring(sigbuf, proof_req)) != 0 || 656 (r = sshbuf_put_string(sigbuf, session_id2, 657 session_id2_len)) != 0 || 658 (r = sshkey_puts(key, sigbuf)) != 0) 659 fatal("%s: couldn't prepare private key " 660 "proof buffer: %s", __func__, ssh_err(r)); 661 if (datlen != sshbuf_len(sigbuf) || 662 memcmp(p, sshbuf_ptr(sigbuf), sshbuf_len(sigbuf)) != 0) 663 fatal("%s: bad data length: %zu, hostkey proof len %zu", 664 __func__, datlen, sshbuf_len(sigbuf)); 665 sshbuf_free(sigbuf); 666 is_proof = 1; 667 } 668 669 /* save session id, it will be passed on the first call */ 670 if (session_id2_len == 0) { 671 session_id2_len = datlen; 672 session_id2 = xmalloc(session_id2_len); 673 memcpy(session_id2, p, session_id2_len); 674 } 675 676 if ((key = get_hostkey_by_index(keyid)) != NULL) { 677 if ((r = sshkey_sign(key, &signature, &siglen, p, datlen, alg, 678 datafellows)) != 0) 679 fatal("%s: sshkey_sign failed: %s", 680 __func__, ssh_err(r)); 681 } else if ((key = get_hostkey_public_by_index(keyid, ssh)) != NULL && 682 auth_sock > 0) { 683 if ((r = ssh_agent_sign(auth_sock, key, &signature, &siglen, 684 p, datlen, alg, datafellows)) != 0) { 685 fatal("%s: ssh_agent_sign failed: %s", 686 __func__, ssh_err(r)); 687 } 688 } else 689 fatal("%s: no hostkey from index %d", __func__, keyid); 690 691 debug3("%s: %s signature %p(%zu)", __func__, 692 is_proof ? "KEX" : "hostkey proof", signature, siglen); 693 694 sshbuf_reset(m); 695 if ((r = sshbuf_put_string(m, signature, siglen)) != 0) 696 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 697 698 free(alg); 699 free(p); 700 free(signature); 701 702 mm_request_send(sock, MONITOR_ANS_SIGN, m); 703 704 /* Turn on permissions for getpwnam */ 705 monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1); 706 707 return (0); 708 } 709 710 /* Retrieves the password entry and also checks if the user is permitted */ 711 712 int 713 mm_answer_pwnamallow(int sock, Buffer *m) 714 { 715 struct ssh *ssh = active_state; /* XXX */ 716 char *username; 717 struct passwd *pwent; 718 int allowed = 0; 719 u_int i; 720 721 debug3("%s", __func__); 722 723 if (authctxt->attempt++ != 0) 724 fatal("%s: multiple attempts for getpwnam", __func__); 725 726 username = buffer_get_string(m, NULL); 727 728 pwent = getpwnamallow(username); 729 730 authctxt->user = xstrdup(username); 731 setproctitle("%s [priv]", pwent ? username : "unknown"); 732 free(username); 733 734 buffer_clear(m); 735 736 if (pwent == NULL) { 737 buffer_put_char(m, 0); 738 authctxt->pw = fakepw(); 739 goto out; 740 } 741 742 allowed = 1; 743 authctxt->pw = pwent; 744 authctxt->valid = 1; 745 746 buffer_put_char(m, 1); 747 buffer_put_string(m, pwent, sizeof(struct passwd)); 748 buffer_put_cstring(m, pwent->pw_name); 749 buffer_put_cstring(m, "*"); 750 #ifdef HAVE_STRUCT_PASSWD_PW_GECOS 751 buffer_put_cstring(m, pwent->pw_gecos); 752 #endif 753 #ifdef HAVE_STRUCT_PASSWD_PW_CLASS 754 buffer_put_cstring(m, pwent->pw_class); 755 #endif 756 buffer_put_cstring(m, pwent->pw_dir); 757 buffer_put_cstring(m, pwent->pw_shell); 758 759 out: 760 ssh_packet_set_log_preamble(ssh, "%suser %s", 761 authctxt->valid ? "authenticating" : "invalid ", authctxt->user); 762 buffer_put_string(m, &options, sizeof(options)); 763 764 #define M_CP_STROPT(x) do { \ 765 if (options.x != NULL) \ 766 buffer_put_cstring(m, options.x); \ 767 } while (0) 768 #define M_CP_STRARRAYOPT(x, nx) do { \ 769 for (i = 0; i < options.nx; i++) \ 770 buffer_put_cstring(m, options.x[i]); \ 771 } while (0) 772 /* See comment in servconf.h */ 773 COPY_MATCH_STRING_OPTS(); 774 #undef M_CP_STROPT 775 #undef M_CP_STRARRAYOPT 776 777 /* Create valid auth method lists */ 778 if (auth2_setup_methods_lists(authctxt) != 0) { 779 /* 780 * The monitor will continue long enough to let the child 781 * run to it's packet_disconnect(), but it must not allow any 782 * authentication to succeed. 783 */ 784 debug("%s: no valid authentication method lists", __func__); 785 } 786 787 debug3("%s: sending MONITOR_ANS_PWNAM: %d", __func__, allowed); 788 mm_request_send(sock, MONITOR_ANS_PWNAM, m); 789 790 /* Allow service/style information on the auth context */ 791 monitor_permit(mon_dispatch, MONITOR_REQ_AUTHSERV, 1); 792 monitor_permit(mon_dispatch, MONITOR_REQ_AUTH2_READ_BANNER, 1); 793 794 #ifdef USE_PAM 795 if (options.use_pam) 796 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_START, 1); 797 #endif 798 799 return (0); 800 } 801 802 int mm_answer_auth2_read_banner(int sock, Buffer *m) 803 { 804 char *banner; 805 806 buffer_clear(m); 807 banner = auth2_read_banner(); 808 buffer_put_cstring(m, banner != NULL ? banner : ""); 809 mm_request_send(sock, MONITOR_ANS_AUTH2_READ_BANNER, m); 810 free(banner); 811 812 return (0); 813 } 814 815 int 816 mm_answer_authserv(int sock, Buffer *m) 817 { 818 monitor_permit_authentications(1); 819 820 authctxt->service = buffer_get_string(m, NULL); 821 authctxt->style = buffer_get_string(m, NULL); 822 debug3("%s: service=%s, style=%s", 823 __func__, authctxt->service, authctxt->style); 824 825 if (strlen(authctxt->style) == 0) { 826 free(authctxt->style); 827 authctxt->style = NULL; 828 } 829 830 return (0); 831 } 832 833 int 834 mm_answer_authpassword(int sock, Buffer *m) 835 { 836 struct ssh *ssh = active_state; /* XXX */ 837 static int call_count; 838 char *passwd; 839 int authenticated; 840 u_int plen; 841 842 if (!options.password_authentication) 843 fatal("%s: password authentication not enabled", __func__); 844 passwd = buffer_get_string(m, &plen); 845 /* Only authenticate if the context is valid */ 846 authenticated = options.password_authentication && 847 auth_password(ssh, passwd); 848 explicit_bzero(passwd, strlen(passwd)); 849 free(passwd); 850 851 buffer_clear(m); 852 buffer_put_int(m, authenticated); 853 #ifdef USE_PAM 854 buffer_put_int(m, sshpam_get_maxtries_reached()); 855 #endif 856 857 debug3("%s: sending result %d", __func__, authenticated); 858 mm_request_send(sock, MONITOR_ANS_AUTHPASSWORD, m); 859 860 call_count++; 861 if (plen == 0 && call_count == 1) 862 auth_method = "none"; 863 else 864 auth_method = "password"; 865 866 /* Causes monitor loop to terminate if authenticated */ 867 return (authenticated); 868 } 869 870 #ifdef BSD_AUTH 871 int 872 mm_answer_bsdauthquery(int sock, Buffer *m) 873 { 874 char *name, *infotxt; 875 u_int numprompts; 876 u_int *echo_on; 877 char **prompts; 878 u_int success; 879 880 if (!options.kbd_interactive_authentication) 881 fatal("%s: kbd-int authentication not enabled", __func__); 882 success = bsdauth_query(authctxt, &name, &infotxt, &numprompts, 883 &prompts, &echo_on) < 0 ? 0 : 1; 884 885 buffer_clear(m); 886 buffer_put_int(m, success); 887 if (success) 888 buffer_put_cstring(m, prompts[0]); 889 890 debug3("%s: sending challenge success: %u", __func__, success); 891 mm_request_send(sock, MONITOR_ANS_BSDAUTHQUERY, m); 892 893 if (success) { 894 free(name); 895 free(infotxt); 896 free(prompts); 897 free(echo_on); 898 } 899 900 return (0); 901 } 902 903 int 904 mm_answer_bsdauthrespond(int sock, Buffer *m) 905 { 906 char *response; 907 int authok; 908 909 if (!options.kbd_interactive_authentication) 910 fatal("%s: kbd-int authentication not enabled", __func__); 911 if (authctxt->as == NULL) 912 fatal("%s: no bsd auth session", __func__); 913 914 response = buffer_get_string(m, NULL); 915 authok = options.challenge_response_authentication && 916 auth_userresponse(authctxt->as, response, 0); 917 authctxt->as = NULL; 918 debug3("%s: <%s> = <%d>", __func__, response, authok); 919 free(response); 920 921 buffer_clear(m); 922 buffer_put_int(m, authok); 923 924 debug3("%s: sending authenticated: %d", __func__, authok); 925 mm_request_send(sock, MONITOR_ANS_BSDAUTHRESPOND, m); 926 927 auth_method = "keyboard-interactive"; 928 auth_submethod = "bsdauth"; 929 930 return (authok != 0); 931 } 932 #endif 933 934 #ifdef SKEY 935 int 936 mm_answer_skeyquery(int sock, Buffer *m) 937 { 938 struct skey skey; 939 char challenge[1024]; 940 u_int success; 941 942 success = _compat_skeychallenge(&skey, authctxt->user, challenge, 943 sizeof(challenge)) < 0 ? 0 : 1; 944 945 buffer_clear(m); 946 buffer_put_int(m, success); 947 if (success) 948 buffer_put_cstring(m, challenge); 949 950 debug3("%s: sending challenge success: %u", __func__, success); 951 mm_request_send(sock, MONITOR_ANS_SKEYQUERY, m); 952 953 return (0); 954 } 955 956 int 957 mm_answer_skeyrespond(int sock, Buffer *m) 958 { 959 char *response; 960 int authok; 961 962 response = buffer_get_string(m, NULL); 963 964 authok = (options.challenge_response_authentication && 965 authctxt->valid && 966 skey_haskey(authctxt->pw->pw_name) == 0 && 967 skey_passcheck(authctxt->pw->pw_name, response) != -1); 968 969 free(response); 970 971 buffer_clear(m); 972 buffer_put_int(m, authok); 973 974 debug3("%s: sending authenticated: %d", __func__, authok); 975 mm_request_send(sock, MONITOR_ANS_SKEYRESPOND, m); 976 977 auth_method = "keyboard-interactive"; 978 auth_submethod = "skey"; 979 980 return (authok != 0); 981 } 982 #endif 983 984 #ifdef USE_PAM 985 int 986 mm_answer_pam_start(int sock, Buffer *m) 987 { 988 if (!options.use_pam) 989 fatal("UsePAM not set, but ended up in %s anyway", __func__); 990 991 start_pam(authctxt); 992 993 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_ACCOUNT, 1); 994 if (options.kbd_interactive_authentication) 995 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_INIT_CTX, 1); 996 997 return (0); 998 } 999 1000 int 1001 mm_answer_pam_account(int sock, Buffer *m) 1002 { 1003 u_int ret; 1004 1005 if (!options.use_pam) 1006 fatal("%s: PAM not enabled", __func__); 1007 1008 ret = do_pam_account(); 1009 1010 buffer_put_int(m, ret); 1011 buffer_put_string(m, buffer_ptr(&loginmsg), buffer_len(&loginmsg)); 1012 1013 mm_request_send(sock, MONITOR_ANS_PAM_ACCOUNT, m); 1014 1015 return (ret); 1016 } 1017 1018 static void *sshpam_ctxt, *sshpam_authok; 1019 extern KbdintDevice sshpam_device; 1020 1021 int 1022 mm_answer_pam_init_ctx(int sock, Buffer *m) 1023 { 1024 debug3("%s", __func__); 1025 if (!options.kbd_interactive_authentication) 1026 fatal("%s: kbd-int authentication not enabled", __func__); 1027 if (sshpam_ctxt != NULL) 1028 fatal("%s: already called", __func__); 1029 sshpam_ctxt = (sshpam_device.init_ctx)(authctxt); 1030 sshpam_authok = NULL; 1031 buffer_clear(m); 1032 if (sshpam_ctxt != NULL) { 1033 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_FREE_CTX, 1); 1034 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_QUERY, 1); 1035 buffer_put_int(m, 1); 1036 } else { 1037 buffer_put_int(m, 0); 1038 } 1039 mm_request_send(sock, MONITOR_ANS_PAM_INIT_CTX, m); 1040 return (0); 1041 } 1042 1043 int 1044 mm_answer_pam_query(int sock, Buffer *m) 1045 { 1046 char *name = NULL, *info = NULL, **prompts = NULL; 1047 u_int i, num = 0, *echo_on = 0; 1048 int ret; 1049 1050 debug3("%s", __func__); 1051 sshpam_authok = NULL; 1052 if (sshpam_ctxt == NULL) 1053 fatal("%s: no context", __func__); 1054 ret = (sshpam_device.query)(sshpam_ctxt, &name, &info, 1055 &num, &prompts, &echo_on); 1056 if (ret == 0 && num == 0) 1057 sshpam_authok = sshpam_ctxt; 1058 if (num > 1 || name == NULL || info == NULL) 1059 fatal("sshpam_device.query failed"); 1060 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_RESPOND, 1); 1061 buffer_clear(m); 1062 buffer_put_int(m, ret); 1063 buffer_put_cstring(m, name); 1064 free(name); 1065 buffer_put_cstring(m, info); 1066 free(info); 1067 buffer_put_int(m, sshpam_get_maxtries_reached()); 1068 buffer_put_int(m, num); 1069 for (i = 0; i < num; ++i) { 1070 buffer_put_cstring(m, prompts[i]); 1071 free(prompts[i]); 1072 buffer_put_int(m, echo_on[i]); 1073 } 1074 free(prompts); 1075 free(echo_on); 1076 auth_method = "keyboard-interactive"; 1077 auth_submethod = "pam"; 1078 mm_request_send(sock, MONITOR_ANS_PAM_QUERY, m); 1079 return (0); 1080 } 1081 1082 int 1083 mm_answer_pam_respond(int sock, Buffer *m) 1084 { 1085 char **resp; 1086 u_int i, num; 1087 int ret; 1088 1089 debug3("%s", __func__); 1090 if (sshpam_ctxt == NULL) 1091 fatal("%s: no context", __func__); 1092 sshpam_authok = NULL; 1093 num = buffer_get_int(m); 1094 if (num > 0) { 1095 resp = xcalloc(num, sizeof(char *)); 1096 for (i = 0; i < num; ++i) 1097 resp[i] = buffer_get_string(m, NULL); 1098 ret = (sshpam_device.respond)(sshpam_ctxt, num, resp); 1099 for (i = 0; i < num; ++i) 1100 free(resp[i]); 1101 free(resp); 1102 } else { 1103 ret = (sshpam_device.respond)(sshpam_ctxt, num, NULL); 1104 } 1105 buffer_clear(m); 1106 buffer_put_int(m, ret); 1107 mm_request_send(sock, MONITOR_ANS_PAM_RESPOND, m); 1108 auth_method = "keyboard-interactive"; 1109 auth_submethod = "pam"; 1110 if (ret == 0) 1111 sshpam_authok = sshpam_ctxt; 1112 return (0); 1113 } 1114 1115 int 1116 mm_answer_pam_free_ctx(int sock, Buffer *m) 1117 { 1118 int r = sshpam_authok != NULL && sshpam_authok == sshpam_ctxt; 1119 1120 debug3("%s", __func__); 1121 if (sshpam_ctxt == NULL) 1122 fatal("%s: no context", __func__); 1123 (sshpam_device.free_ctx)(sshpam_ctxt); 1124 sshpam_ctxt = sshpam_authok = NULL; 1125 buffer_clear(m); 1126 mm_request_send(sock, MONITOR_ANS_PAM_FREE_CTX, m); 1127 /* Allow another attempt */ 1128 monitor_permit(mon_dispatch, MONITOR_REQ_PAM_INIT_CTX, 1); 1129 auth_method = "keyboard-interactive"; 1130 auth_submethod = "pam"; 1131 return r; 1132 } 1133 #endif 1134 1135 int 1136 mm_answer_keyallowed(int sock, Buffer *m) 1137 { 1138 struct ssh *ssh = active_state; /* XXX */ 1139 struct sshkey *key; 1140 char *cuser, *chost; 1141 u_char *blob; 1142 u_int bloblen, pubkey_auth_attempt; 1143 enum mm_keytype type = 0; 1144 int r, allowed = 0; 1145 struct sshauthopt *opts = NULL; 1146 1147 debug3("%s entering", __func__); 1148 type = buffer_get_int(m); 1149 cuser = buffer_get_string(m, NULL); 1150 chost = buffer_get_string(m, NULL); 1151 blob = buffer_get_string(m, &bloblen); 1152 pubkey_auth_attempt = buffer_get_int(m); 1153 1154 key = key_from_blob(blob, bloblen); 1155 1156 debug3("%s: key_from_blob: %p", __func__, key); 1157 1158 if (key != NULL && authctxt->valid) { 1159 /* These should not make it past the privsep child */ 1160 if (key_type_plain(key->type) == KEY_RSA && 1161 (datafellows & SSH_BUG_RSASIGMD5) != 0) 1162 fatal("%s: passed a SSH_BUG_RSASIGMD5 key", __func__); 1163 1164 switch (type) { 1165 case MM_USERKEY: 1166 auth_method = "publickey"; 1167 if (!options.pubkey_authentication) 1168 break; 1169 if (auth2_key_already_used(authctxt, key)) 1170 break; 1171 if (match_pattern_list(sshkey_ssh_name(key), 1172 options.pubkey_key_types, 0) != 1) 1173 break; 1174 allowed = user_key_allowed(ssh, authctxt->pw, key, 1175 pubkey_auth_attempt, &opts); 1176 break; 1177 case MM_HOSTKEY: 1178 auth_method = "hostbased"; 1179 if (!options.hostbased_authentication) 1180 break; 1181 if (auth2_key_already_used(authctxt, key)) 1182 break; 1183 if (match_pattern_list(sshkey_ssh_name(key), 1184 options.hostbased_key_types, 0) != 1) 1185 break; 1186 allowed = hostbased_key_allowed(authctxt->pw, 1187 cuser, chost, key); 1188 auth2_record_info(authctxt, 1189 "client user \"%.100s\", client host \"%.100s\"", 1190 cuser, chost); 1191 break; 1192 default: 1193 fatal("%s: unknown key type %d", __func__, type); 1194 break; 1195 } 1196 } 1197 1198 debug3("%s: %s authentication%s: %s key is %s", __func__, 1199 auth_method, pubkey_auth_attempt ? "" : " test", 1200 (key == NULL || !authctxt->valid) ? "invalid" : sshkey_type(key), 1201 allowed ? "allowed" : "not allowed"); 1202 1203 auth2_record_key(authctxt, 0, key); 1204 sshkey_free(key); 1205 1206 /* clear temporarily storage (used by verify) */ 1207 monitor_reset_key_state(); 1208 1209 if (allowed) { 1210 /* Save temporarily for comparison in verify */ 1211 key_blob = blob; 1212 key_bloblen = bloblen; 1213 key_blobtype = type; 1214 key_opts = opts; 1215 hostbased_cuser = cuser; 1216 hostbased_chost = chost; 1217 } else { 1218 /* Log failed attempt */ 1219 auth_log(authctxt, 0, 0, auth_method, NULL); 1220 free(blob); 1221 free(cuser); 1222 free(chost); 1223 } 1224 1225 buffer_clear(m); 1226 buffer_put_int(m, allowed); 1227 if (opts != NULL && (r = sshauthopt_serialise(opts, m, 1)) != 0) 1228 fatal("%s: sshauthopt_serialise: %s", __func__, ssh_err(r)); 1229 mm_request_send(sock, MONITOR_ANS_KEYALLOWED, m); 1230 1231 if (!allowed) 1232 sshauthopt_free(opts); 1233 1234 return (0); 1235 } 1236 1237 static int 1238 monitor_valid_userblob(u_char *data, u_int datalen) 1239 { 1240 Buffer b; 1241 u_char *p; 1242 char *userstyle, *cp; 1243 u_int len; 1244 int fail = 0; 1245 1246 buffer_init(&b); 1247 buffer_append(&b, data, datalen); 1248 1249 if (datafellows & SSH_OLD_SESSIONID) { 1250 p = buffer_ptr(&b); 1251 len = buffer_len(&b); 1252 if ((session_id2 == NULL) || 1253 (len < session_id2_len) || 1254 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) 1255 fail++; 1256 buffer_consume(&b, session_id2_len); 1257 } else { 1258 p = buffer_get_string(&b, &len); 1259 if ((session_id2 == NULL) || 1260 (len != session_id2_len) || 1261 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) 1262 fail++; 1263 free(p); 1264 } 1265 if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST) 1266 fail++; 1267 cp = buffer_get_cstring(&b, NULL); 1268 xasprintf(&userstyle, "%s%s%s", authctxt->user, 1269 authctxt->style ? ":" : "", 1270 authctxt->style ? authctxt->style : ""); 1271 if (strcmp(userstyle, cp) != 0) { 1272 logit("wrong user name passed to monitor: " 1273 "expected %s != %.100s", userstyle, cp); 1274 fail++; 1275 } 1276 free(userstyle); 1277 free(cp); 1278 buffer_skip_string(&b); 1279 cp = buffer_get_cstring(&b, NULL); 1280 if (strcmp("publickey", cp) != 0) 1281 fail++; 1282 free(cp); 1283 if (!buffer_get_char(&b)) 1284 fail++; 1285 buffer_skip_string(&b); 1286 buffer_skip_string(&b); 1287 if (buffer_len(&b) != 0) 1288 fail++; 1289 buffer_free(&b); 1290 return (fail == 0); 1291 } 1292 1293 static int 1294 monitor_valid_hostbasedblob(u_char *data, u_int datalen, char *cuser, 1295 char *chost) 1296 { 1297 Buffer b; 1298 char *p, *userstyle; 1299 u_int len; 1300 int fail = 0; 1301 1302 buffer_init(&b); 1303 buffer_append(&b, data, datalen); 1304 1305 p = buffer_get_string(&b, &len); 1306 if ((session_id2 == NULL) || 1307 (len != session_id2_len) || 1308 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) 1309 fail++; 1310 free(p); 1311 1312 if (buffer_get_char(&b) != SSH2_MSG_USERAUTH_REQUEST) 1313 fail++; 1314 p = buffer_get_cstring(&b, NULL); 1315 xasprintf(&userstyle, "%s%s%s", authctxt->user, 1316 authctxt->style ? ":" : "", 1317 authctxt->style ? authctxt->style : ""); 1318 if (strcmp(userstyle, p) != 0) { 1319 logit("wrong user name passed to monitor: expected %s != %.100s", 1320 userstyle, p); 1321 fail++; 1322 } 1323 free(userstyle); 1324 free(p); 1325 buffer_skip_string(&b); /* service */ 1326 p = buffer_get_cstring(&b, NULL); 1327 if (strcmp(p, "hostbased") != 0) 1328 fail++; 1329 free(p); 1330 buffer_skip_string(&b); /* pkalg */ 1331 buffer_skip_string(&b); /* pkblob */ 1332 1333 /* verify client host, strip trailing dot if necessary */ 1334 p = buffer_get_string(&b, NULL); 1335 if (((len = strlen(p)) > 0) && p[len - 1] == '.') 1336 p[len - 1] = '\0'; 1337 if (strcmp(p, chost) != 0) 1338 fail++; 1339 free(p); 1340 1341 /* verify client user */ 1342 p = buffer_get_string(&b, NULL); 1343 if (strcmp(p, cuser) != 0) 1344 fail++; 1345 free(p); 1346 1347 if (buffer_len(&b) != 0) 1348 fail++; 1349 buffer_free(&b); 1350 return (fail == 0); 1351 } 1352 1353 int 1354 mm_answer_keyverify(int sock, struct sshbuf *m) 1355 { 1356 struct ssh *ssh = active_state; /* XXX */ 1357 struct sshkey *key; 1358 u_char *signature, *data, *blob; 1359 char *sigalg; 1360 size_t signaturelen, datalen, bloblen; 1361 int r, ret, valid_data = 0, encoded_ret; 1362 1363 if ((r = sshbuf_get_string(m, &blob, &bloblen)) != 0 || 1364 (r = sshbuf_get_string(m, &signature, &signaturelen)) != 0 || 1365 (r = sshbuf_get_string(m, &data, &datalen)) != 0 || 1366 (r = sshbuf_get_cstring(m, &sigalg, NULL)) != 0) 1367 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1368 1369 if (hostbased_cuser == NULL || hostbased_chost == NULL || 1370 !monitor_allowed_key(blob, bloblen)) 1371 fatal("%s: bad key, not previously allowed", __func__); 1372 1373 /* Empty signature algorithm means NULL. */ 1374 if (*sigalg == '\0') { 1375 free(sigalg); 1376 sigalg = NULL; 1377 } 1378 1379 /* XXX use sshkey_froms here; need to change key_blob, etc. */ 1380 if ((r = sshkey_from_blob(blob, bloblen, &key)) != 0) 1381 fatal("%s: bad public key blob: %s", __func__, ssh_err(r)); 1382 1383 switch (key_blobtype) { 1384 case MM_USERKEY: 1385 valid_data = monitor_valid_userblob(data, datalen); 1386 auth_method = "publickey"; 1387 break; 1388 case MM_HOSTKEY: 1389 valid_data = monitor_valid_hostbasedblob(data, datalen, 1390 hostbased_cuser, hostbased_chost); 1391 auth_method = "hostbased"; 1392 break; 1393 default: 1394 valid_data = 0; 1395 break; 1396 } 1397 if (!valid_data) 1398 fatal("%s: bad signature data blob", __func__); 1399 1400 ret = sshkey_verify(key, signature, signaturelen, data, datalen, 1401 sigalg, active_state->compat); 1402 debug3("%s: %s %p signature %s", __func__, auth_method, key, 1403 (ret == 0) ? "verified" : "unverified"); 1404 auth2_record_key(authctxt, ret == 0, key); 1405 1406 free(blob); 1407 free(signature); 1408 free(data); 1409 free(sigalg); 1410 1411 if (key_blobtype == MM_USERKEY) 1412 auth_activate_options(ssh, key_opts); 1413 monitor_reset_key_state(); 1414 1415 sshkey_free(key); 1416 sshbuf_reset(m); 1417 1418 /* encode ret != 0 as positive integer, since we're sending u32 */ 1419 encoded_ret = (ret != 0); 1420 if ((r = sshbuf_put_u32(m, encoded_ret)) != 0) 1421 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1422 mm_request_send(sock, MONITOR_ANS_KEYVERIFY, m); 1423 1424 return ret == 0; 1425 } 1426 1427 static void 1428 mm_record_login(Session *s, struct passwd *pw) 1429 { 1430 struct ssh *ssh = active_state; /* XXX */ 1431 socklen_t fromlen; 1432 struct sockaddr_storage from; 1433 1434 /* 1435 * Get IP address of client. If the connection is not a socket, let 1436 * the address be 0.0.0.0. 1437 */ 1438 memset(&from, 0, sizeof(from)); 1439 fromlen = sizeof(from); 1440 if (packet_connection_is_on_socket()) { 1441 if (getpeername(packet_get_connection_in(), 1442 (struct sockaddr *)&from, &fromlen) < 0) { 1443 debug("getpeername: %.100s", strerror(errno)); 1444 cleanup_exit(255); 1445 } 1446 } 1447 /* Record that there was a login on that tty from the remote host. */ 1448 record_login(s->pid, s->tty, pw->pw_name, pw->pw_uid, 1449 session_get_remote_name_or_ip(ssh, utmp_len, options.use_dns), 1450 (struct sockaddr *)&from, fromlen); 1451 } 1452 1453 static void 1454 mm_session_close(Session *s) 1455 { 1456 debug3("%s: session %d pid %ld", __func__, s->self, (long)s->pid); 1457 if (s->ttyfd != -1) { 1458 debug3("%s: tty %s ptyfd %d", __func__, s->tty, s->ptyfd); 1459 session_pty_cleanup2(s); 1460 } 1461 session_unused(s->self); 1462 } 1463 1464 int 1465 mm_answer_pty(int sock, Buffer *m) 1466 { 1467 extern struct monitor *pmonitor; 1468 Session *s; 1469 int res, fd0; 1470 1471 debug3("%s entering", __func__); 1472 1473 buffer_clear(m); 1474 s = session_new(); 1475 if (s == NULL) 1476 goto error; 1477 s->authctxt = authctxt; 1478 s->pw = authctxt->pw; 1479 s->pid = pmonitor->m_pid; 1480 res = pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty)); 1481 if (res == 0) 1482 goto error; 1483 pty_setowner(authctxt->pw, s->tty); 1484 1485 buffer_put_int(m, 1); 1486 buffer_put_cstring(m, s->tty); 1487 1488 /* We need to trick ttyslot */ 1489 if (dup2(s->ttyfd, 0) == -1) 1490 fatal("%s: dup2", __func__); 1491 1492 mm_record_login(s, authctxt->pw); 1493 1494 /* Now we can close the file descriptor again */ 1495 close(0); 1496 1497 /* send messages generated by record_login */ 1498 buffer_put_string(m, buffer_ptr(&loginmsg), buffer_len(&loginmsg)); 1499 buffer_clear(&loginmsg); 1500 1501 mm_request_send(sock, MONITOR_ANS_PTY, m); 1502 1503 if (mm_send_fd(sock, s->ptyfd) == -1 || 1504 mm_send_fd(sock, s->ttyfd) == -1) 1505 fatal("%s: send fds failed", __func__); 1506 1507 /* make sure nothing uses fd 0 */ 1508 if ((fd0 = open(_PATH_DEVNULL, O_RDONLY)) < 0) 1509 fatal("%s: open(/dev/null): %s", __func__, strerror(errno)); 1510 if (fd0 != 0) 1511 error("%s: fd0 %d != 0", __func__, fd0); 1512 1513 /* slave is not needed */ 1514 close(s->ttyfd); 1515 s->ttyfd = s->ptyfd; 1516 /* no need to dup() because nobody closes ptyfd */ 1517 s->ptymaster = s->ptyfd; 1518 1519 debug3("%s: tty %s ptyfd %d", __func__, s->tty, s->ttyfd); 1520 1521 return (0); 1522 1523 error: 1524 if (s != NULL) 1525 mm_session_close(s); 1526 buffer_put_int(m, 0); 1527 mm_request_send(sock, MONITOR_ANS_PTY, m); 1528 return (0); 1529 } 1530 1531 int 1532 mm_answer_pty_cleanup(int sock, Buffer *m) 1533 { 1534 Session *s; 1535 char *tty; 1536 1537 debug3("%s entering", __func__); 1538 1539 tty = buffer_get_string(m, NULL); 1540 if ((s = session_by_tty(tty)) != NULL) 1541 mm_session_close(s); 1542 buffer_clear(m); 1543 free(tty); 1544 return (0); 1545 } 1546 1547 int 1548 mm_answer_term(int sock, Buffer *req) 1549 { 1550 struct ssh *ssh = active_state; /* XXX */ 1551 extern struct monitor *pmonitor; 1552 int res, status; 1553 1554 debug3("%s: tearing down sessions", __func__); 1555 1556 /* The child is terminating */ 1557 session_destroy_all(ssh, &mm_session_close); 1558 1559 #ifdef USE_PAM 1560 if (options.use_pam) 1561 sshpam_cleanup(); 1562 #endif 1563 1564 while (waitpid(pmonitor->m_pid, &status, 0) == -1) 1565 if (errno != EINTR) 1566 exit(1); 1567 1568 res = WIFEXITED(status) ? WEXITSTATUS(status) : 1; 1569 1570 /* Terminate process */ 1571 exit(res); 1572 } 1573 1574 #ifdef SSH_AUDIT_EVENTS 1575 /* Report that an audit event occurred */ 1576 int 1577 mm_answer_audit_event(int socket, Buffer *m) 1578 { 1579 ssh_audit_event_t event; 1580 1581 debug3("%s entering", __func__); 1582 1583 event = buffer_get_int(m); 1584 switch(event) { 1585 case SSH_AUTH_FAIL_PUBKEY: 1586 case SSH_AUTH_FAIL_HOSTBASED: 1587 case SSH_AUTH_FAIL_GSSAPI: 1588 case SSH_LOGIN_EXCEED_MAXTRIES: 1589 case SSH_LOGIN_ROOT_DENIED: 1590 case SSH_CONNECTION_CLOSE: 1591 case SSH_INVALID_USER: 1592 audit_event(event); 1593 break; 1594 default: 1595 fatal("Audit event type %d not permitted", event); 1596 } 1597 1598 return (0); 1599 } 1600 1601 int 1602 mm_answer_audit_command(int socket, Buffer *m) 1603 { 1604 u_int len; 1605 char *cmd; 1606 1607 debug3("%s entering", __func__); 1608 cmd = buffer_get_string(m, &len); 1609 /* sanity check command, if so how? */ 1610 audit_run_command(cmd); 1611 free(cmd); 1612 return (0); 1613 } 1614 #endif /* SSH_AUDIT_EVENTS */ 1615 1616 void 1617 monitor_clear_keystate(struct monitor *pmonitor) 1618 { 1619 struct ssh *ssh = active_state; /* XXX */ 1620 1621 ssh_clear_newkeys(ssh, MODE_IN); 1622 ssh_clear_newkeys(ssh, MODE_OUT); 1623 sshbuf_free(child_state); 1624 child_state = NULL; 1625 } 1626 1627 void 1628 monitor_apply_keystate(struct monitor *pmonitor) 1629 { 1630 struct ssh *ssh = active_state; /* XXX */ 1631 struct kex *kex; 1632 int r; 1633 1634 debug3("%s: packet_set_state", __func__); 1635 if ((r = ssh_packet_set_state(ssh, child_state)) != 0) 1636 fatal("%s: packet_set_state: %s", __func__, ssh_err(r)); 1637 sshbuf_free(child_state); 1638 child_state = NULL; 1639 1640 if ((kex = ssh->kex) != NULL) { 1641 /* XXX set callbacks */ 1642 #ifdef WITH_OPENSSL 1643 kex->kex[KEX_DH_GRP1_SHA1] = kexdh_server; 1644 kex->kex[KEX_DH_GRP14_SHA1] = kexdh_server; 1645 kex->kex[KEX_DH_GRP14_SHA256] = kexdh_server; 1646 kex->kex[KEX_DH_GRP16_SHA512] = kexdh_server; 1647 kex->kex[KEX_DH_GRP18_SHA512] = kexdh_server; 1648 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 1649 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 1650 # ifdef OPENSSL_HAS_ECC 1651 kex->kex[KEX_ECDH_SHA2] = kexecdh_server; 1652 # endif 1653 #endif /* WITH_OPENSSL */ 1654 kex->kex[KEX_C25519_SHA256] = kexc25519_server; 1655 kex->load_host_public_key=&get_hostkey_public_by_type; 1656 kex->load_host_private_key=&get_hostkey_private_by_type; 1657 kex->host_key_index=&get_hostkey_index; 1658 kex->sign = sshd_hostkey_sign; 1659 } 1660 } 1661 1662 /* This function requries careful sanity checking */ 1663 1664 void 1665 mm_get_keystate(struct monitor *pmonitor) 1666 { 1667 debug3("%s: Waiting for new keys", __func__); 1668 1669 if ((child_state = sshbuf_new()) == NULL) 1670 fatal("%s: sshbuf_new failed", __func__); 1671 mm_request_receive_expect(pmonitor->m_sendfd, MONITOR_REQ_KEYEXPORT, 1672 child_state); 1673 debug3("%s: GOT new keys", __func__); 1674 } 1675 1676 1677 /* XXX */ 1678 1679 #define FD_CLOSEONEXEC(x) do { \ 1680 if (fcntl(x, F_SETFD, FD_CLOEXEC) == -1) \ 1681 fatal("fcntl(%d, F_SETFD)", x); \ 1682 } while (0) 1683 1684 static void 1685 monitor_openfds(struct monitor *mon, int do_logfds) 1686 { 1687 int pair[2]; 1688 #ifdef SO_ZEROIZE 1689 int on = 1; 1690 #endif 1691 1692 if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) 1693 fatal("%s: socketpair: %s", __func__, strerror(errno)); 1694 #ifdef SO_ZEROIZE 1695 if (setsockopt(pair[0], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) < 0) 1696 error("setsockopt SO_ZEROIZE(0): %.100s", strerror(errno)); 1697 if (setsockopt(pair[1], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) < 0) 1698 error("setsockopt SO_ZEROIZE(1): %.100s", strerror(errno)); 1699 #endif 1700 FD_CLOSEONEXEC(pair[0]); 1701 FD_CLOSEONEXEC(pair[1]); 1702 mon->m_recvfd = pair[0]; 1703 mon->m_sendfd = pair[1]; 1704 1705 if (do_logfds) { 1706 if (pipe(pair) == -1) 1707 fatal("%s: pipe: %s", __func__, strerror(errno)); 1708 FD_CLOSEONEXEC(pair[0]); 1709 FD_CLOSEONEXEC(pair[1]); 1710 mon->m_log_recvfd = pair[0]; 1711 mon->m_log_sendfd = pair[1]; 1712 } else 1713 mon->m_log_recvfd = mon->m_log_sendfd = -1; 1714 } 1715 1716 #define MM_MEMSIZE 65536 1717 1718 struct monitor * 1719 monitor_init(void) 1720 { 1721 struct monitor *mon; 1722 1723 mon = xcalloc(1, sizeof(*mon)); 1724 monitor_openfds(mon, 1); 1725 1726 return mon; 1727 } 1728 1729 void 1730 monitor_reinit(struct monitor *mon) 1731 { 1732 monitor_openfds(mon, 0); 1733 } 1734 1735 #ifdef GSSAPI 1736 int 1737 mm_answer_gss_setup_ctx(int sock, Buffer *m) 1738 { 1739 gss_OID_desc goid; 1740 OM_uint32 major; 1741 u_int len; 1742 1743 if (!options.gss_authentication) 1744 fatal("%s: GSSAPI authentication not enabled", __func__); 1745 1746 goid.elements = buffer_get_string(m, &len); 1747 goid.length = len; 1748 1749 major = ssh_gssapi_server_ctx(&gsscontext, &goid); 1750 1751 free(goid.elements); 1752 1753 buffer_clear(m); 1754 buffer_put_int(m, major); 1755 1756 mm_request_send(sock, MONITOR_ANS_GSSSETUP, m); 1757 1758 /* Now we have a context, enable the step */ 1759 monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 1); 1760 1761 return (0); 1762 } 1763 1764 int 1765 mm_answer_gss_accept_ctx(int sock, Buffer *m) 1766 { 1767 gss_buffer_desc in; 1768 gss_buffer_desc out = GSS_C_EMPTY_BUFFER; 1769 OM_uint32 major, minor; 1770 OM_uint32 flags = 0; /* GSI needs this */ 1771 u_int len; 1772 1773 if (!options.gss_authentication) 1774 fatal("%s: GSSAPI authentication not enabled", __func__); 1775 1776 in.value = buffer_get_string(m, &len); 1777 in.length = len; 1778 major = ssh_gssapi_accept_ctx(gsscontext, &in, &out, &flags); 1779 free(in.value); 1780 1781 buffer_clear(m); 1782 buffer_put_int(m, major); 1783 buffer_put_string(m, out.value, out.length); 1784 buffer_put_int(m, flags); 1785 mm_request_send(sock, MONITOR_ANS_GSSSTEP, m); 1786 1787 gss_release_buffer(&minor, &out); 1788 1789 if (major == GSS_S_COMPLETE) { 1790 monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 0); 1791 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1); 1792 monitor_permit(mon_dispatch, MONITOR_REQ_GSSCHECKMIC, 1); 1793 } 1794 return (0); 1795 } 1796 1797 int 1798 mm_answer_gss_checkmic(int sock, Buffer *m) 1799 { 1800 gss_buffer_desc gssbuf, mic; 1801 OM_uint32 ret; 1802 u_int len; 1803 1804 if (!options.gss_authentication) 1805 fatal("%s: GSSAPI authentication not enabled", __func__); 1806 1807 gssbuf.value = buffer_get_string(m, &len); 1808 gssbuf.length = len; 1809 mic.value = buffer_get_string(m, &len); 1810 mic.length = len; 1811 1812 ret = ssh_gssapi_checkmic(gsscontext, &gssbuf, &mic); 1813 1814 free(gssbuf.value); 1815 free(mic.value); 1816 1817 buffer_clear(m); 1818 buffer_put_int(m, ret); 1819 1820 mm_request_send(sock, MONITOR_ANS_GSSCHECKMIC, m); 1821 1822 if (!GSS_ERROR(ret)) 1823 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1); 1824 1825 return (0); 1826 } 1827 1828 int 1829 mm_answer_gss_userok(int sock, Buffer *m) 1830 { 1831 int authenticated; 1832 const char *displayname; 1833 1834 if (!options.gss_authentication) 1835 fatal("%s: GSSAPI authentication not enabled", __func__); 1836 1837 authenticated = authctxt->valid && ssh_gssapi_userok(authctxt->user); 1838 1839 buffer_clear(m); 1840 buffer_put_int(m, authenticated); 1841 1842 debug3("%s: sending result %d", __func__, authenticated); 1843 mm_request_send(sock, MONITOR_ANS_GSSUSEROK, m); 1844 1845 auth_method = "gssapi-with-mic"; 1846 1847 if ((displayname = ssh_gssapi_displayname()) != NULL) 1848 auth2_record_info(authctxt, "%s", displayname); 1849 1850 /* Monitor loop will terminate if authenticated */ 1851 return (authenticated); 1852 } 1853 #endif /* GSSAPI */ 1854 1855