1 /* $OpenBSD: monitor.c,v 1.239 2024/05/17 06:42:04 jsg Exp $ */ 2 /* 3 * Copyright 2002 Niels Provos <provos@citi.umich.edu> 4 * Copyright 2002 Markus Friedl <markus@openbsd.org> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #include <sys/types.h> 29 #include <sys/wait.h> 30 #include <sys/socket.h> 31 #include <sys/tree.h> 32 #include <sys/queue.h> 33 34 #ifdef WITH_OPENSSL 35 #include <openssl/dh.h> 36 #endif 37 38 #include <errno.h> 39 #include <fcntl.h> 40 #include <limits.h> 41 #include <paths.h> 42 #include <poll.h> 43 #include <pwd.h> 44 #include <signal.h> 45 #include <stdarg.h> 46 #include <stdint.h> 47 #include <stdio.h> 48 #include <stdlib.h> 49 #include <string.h> 50 #include <unistd.h> 51 52 #include "atomicio.h" 53 #include "xmalloc.h" 54 #include "ssh.h" 55 #include "sshkey.h" 56 #include "sshbuf.h" 57 #include "hostfile.h" 58 #include "auth.h" 59 #include "cipher.h" 60 #include "kex.h" 61 #include "dh.h" 62 #include "packet.h" 63 #include "auth-options.h" 64 #include "sshpty.h" 65 #include "channels.h" 66 #include "session.h" 67 #include "sshlogin.h" 68 #include "canohost.h" 69 #include "log.h" 70 #include "misc.h" 71 #include "servconf.h" 72 #include "monitor.h" 73 #ifdef GSSAPI 74 #include "ssh-gss.h" 75 #endif 76 #include "monitor_wrap.h" 77 #include "monitor_fdpass.h" 78 #include "compat.h" 79 #include "ssh2.h" 80 #include "authfd.h" 81 #include "match.h" 82 #include "ssherr.h" 83 #include "sk-api.h" 84 85 #ifdef GSSAPI 86 static Gssctxt *gsscontext = NULL; 87 #endif 88 89 /* Imports */ 90 extern ServerOptions options; 91 extern u_int utmp_len; 92 extern struct sshbuf *loginmsg; 93 extern struct sshauthopt *auth_opts; /* XXX move to permanent ssh->authctxt? */ 94 95 /* State exported from the child */ 96 static struct sshbuf *child_state; 97 98 /* Functions on the monitor that answer unprivileged requests */ 99 100 int mm_answer_moduli(struct ssh *, int, struct sshbuf *); 101 int mm_answer_sign(struct ssh *, int, struct sshbuf *); 102 int mm_answer_pwnamallow(struct ssh *, int, struct sshbuf *); 103 int mm_answer_auth2_read_banner(struct ssh *, int, struct sshbuf *); 104 int mm_answer_authserv(struct ssh *, int, struct sshbuf *); 105 int mm_answer_authpassword(struct ssh *, int, struct sshbuf *); 106 int mm_answer_bsdauthquery(struct ssh *, int, struct sshbuf *); 107 int mm_answer_bsdauthrespond(struct ssh *, int, struct sshbuf *); 108 int mm_answer_keyallowed(struct ssh *, int, struct sshbuf *); 109 int mm_answer_keyverify(struct ssh *, int, struct sshbuf *); 110 int mm_answer_pty(struct ssh *, int, struct sshbuf *); 111 int mm_answer_pty_cleanup(struct ssh *, int, struct sshbuf *); 112 int mm_answer_term(struct ssh *, int, struct sshbuf *); 113 114 #ifdef GSSAPI 115 int mm_answer_gss_setup_ctx(struct ssh *, int, struct sshbuf *); 116 int mm_answer_gss_accept_ctx(struct ssh *, int, struct sshbuf *); 117 int mm_answer_gss_userok(struct ssh *, int, struct sshbuf *); 118 int mm_answer_gss_checkmic(struct ssh *, int, struct sshbuf *); 119 #endif 120 121 static Authctxt *authctxt; 122 123 /* local state for key verify */ 124 static u_char *key_blob = NULL; 125 static size_t key_bloblen = 0; 126 static u_int key_blobtype = MM_NOKEY; 127 static struct sshauthopt *key_opts = NULL; 128 static char *hostbased_cuser = NULL; 129 static char *hostbased_chost = NULL; 130 static char *auth_method = "unknown"; 131 static char *auth_submethod = NULL; 132 static u_int session_id2_len = 0; 133 static u_char *session_id2 = NULL; 134 static pid_t monitor_child_pid; 135 136 struct mon_table { 137 enum monitor_reqtype type; 138 int flags; 139 int (*f)(struct ssh *, int, struct sshbuf *); 140 }; 141 142 #define MON_ISAUTH 0x0004 /* Required for Authentication */ 143 #define MON_AUTHDECIDE 0x0008 /* Decides Authentication */ 144 #define MON_ONCE 0x0010 /* Disable after calling */ 145 #define MON_ALOG 0x0020 /* Log auth attempt without authenticating */ 146 147 #define MON_AUTH (MON_ISAUTH|MON_AUTHDECIDE) 148 149 #define MON_PERMIT 0x1000 /* Request is permitted */ 150 151 static int monitor_read(struct ssh *, struct monitor *, struct mon_table *, 152 struct mon_table **); 153 static int monitor_read_log(struct monitor *); 154 155 struct mon_table mon_dispatch_proto20[] = { 156 #ifdef WITH_OPENSSL 157 {MONITOR_REQ_MODULI, MON_ONCE, mm_answer_moduli}, 158 #endif 159 {MONITOR_REQ_SIGN, MON_ONCE, mm_answer_sign}, 160 {MONITOR_REQ_PWNAM, MON_ONCE, mm_answer_pwnamallow}, 161 {MONITOR_REQ_AUTHSERV, MON_ONCE, mm_answer_authserv}, 162 {MONITOR_REQ_AUTH2_READ_BANNER, MON_ONCE, mm_answer_auth2_read_banner}, 163 {MONITOR_REQ_AUTHPASSWORD, MON_AUTH, mm_answer_authpassword}, 164 {MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery}, 165 {MONITOR_REQ_BSDAUTHRESPOND, MON_AUTH, mm_answer_bsdauthrespond}, 166 {MONITOR_REQ_KEYALLOWED, MON_ISAUTH, mm_answer_keyallowed}, 167 {MONITOR_REQ_KEYVERIFY, MON_AUTH, mm_answer_keyverify}, 168 #ifdef GSSAPI 169 {MONITOR_REQ_GSSSETUP, MON_ISAUTH, mm_answer_gss_setup_ctx}, 170 {MONITOR_REQ_GSSSTEP, 0, mm_answer_gss_accept_ctx}, 171 {MONITOR_REQ_GSSUSEROK, MON_ONCE|MON_AUTHDECIDE, mm_answer_gss_userok}, 172 {MONITOR_REQ_GSSCHECKMIC, MON_ONCE, mm_answer_gss_checkmic}, 173 #endif 174 {0, 0, NULL} 175 }; 176 177 struct mon_table mon_dispatch_postauth20[] = { 178 #ifdef WITH_OPENSSL 179 {MONITOR_REQ_MODULI, 0, mm_answer_moduli}, 180 #endif 181 {MONITOR_REQ_SIGN, 0, mm_answer_sign}, 182 {MONITOR_REQ_PTY, 0, mm_answer_pty}, 183 {MONITOR_REQ_PTYCLEANUP, 0, mm_answer_pty_cleanup}, 184 {MONITOR_REQ_TERM, 0, mm_answer_term}, 185 {0, 0, NULL} 186 }; 187 188 struct mon_table *mon_dispatch; 189 190 /* Specifies if a certain message is allowed at the moment */ 191 static void 192 monitor_permit(struct mon_table *ent, enum monitor_reqtype type, int permit) 193 { 194 while (ent->f != NULL) { 195 if (ent->type == type) { 196 ent->flags &= ~MON_PERMIT; 197 ent->flags |= permit ? MON_PERMIT : 0; 198 return; 199 } 200 ent++; 201 } 202 } 203 204 static void 205 monitor_permit_authentications(int permit) 206 { 207 struct mon_table *ent = mon_dispatch; 208 209 while (ent->f != NULL) { 210 if (ent->flags & MON_AUTH) { 211 ent->flags &= ~MON_PERMIT; 212 ent->flags |= permit ? MON_PERMIT : 0; 213 } 214 ent++; 215 } 216 } 217 218 void 219 monitor_child_preauth(struct ssh *ssh, struct monitor *pmonitor) 220 { 221 struct mon_table *ent; 222 int authenticated = 0, partial = 0; 223 224 debug3("preauth child monitor started"); 225 226 if (pmonitor->m_recvfd >= 0) 227 close(pmonitor->m_recvfd); 228 if (pmonitor->m_log_sendfd >= 0) 229 close(pmonitor->m_log_sendfd); 230 pmonitor->m_log_sendfd = pmonitor->m_recvfd = -1; 231 232 authctxt = (Authctxt *)ssh->authctxt; 233 memset(authctxt, 0, sizeof(*authctxt)); 234 ssh->authctxt = authctxt; 235 236 mon_dispatch = mon_dispatch_proto20; 237 /* Permit requests for moduli and signatures */ 238 monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); 239 monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); 240 241 /* The first few requests do not require asynchronous access */ 242 while (!authenticated) { 243 partial = 0; 244 auth_method = "unknown"; 245 auth_submethod = NULL; 246 auth2_authctxt_reset_info(authctxt); 247 248 authenticated = (monitor_read(ssh, pmonitor, 249 mon_dispatch, &ent) == 1); 250 251 /* Special handling for multiple required authentications */ 252 if (options.num_auth_methods != 0) { 253 if (authenticated && 254 !auth2_update_methods_lists(authctxt, 255 auth_method, auth_submethod)) { 256 debug3_f("method %s: partial", auth_method); 257 authenticated = 0; 258 partial = 1; 259 } 260 } 261 262 if (authenticated) { 263 if (!(ent->flags & MON_AUTHDECIDE)) 264 fatal_f("unexpected authentication from %d", 265 ent->type); 266 if (authctxt->pw->pw_uid == 0 && 267 !auth_root_allowed(ssh, auth_method)) 268 authenticated = 0; 269 } 270 if (ent->flags & (MON_AUTHDECIDE|MON_ALOG)) { 271 auth_log(ssh, authenticated, partial, 272 auth_method, auth_submethod); 273 if (!partial && !authenticated) 274 authctxt->failures++; 275 if (authenticated || partial) { 276 auth2_update_session_info(authctxt, 277 auth_method, auth_submethod); 278 } 279 } 280 if (authctxt->failures > options.max_authtries) { 281 /* Shouldn't happen */ 282 fatal_f("privsep child made too many authentication " 283 "attempts"); 284 } 285 } 286 287 if (!authctxt->valid) 288 fatal_f("authenticated invalid user"); 289 if (strcmp(auth_method, "unknown") == 0) 290 fatal_f("authentication method name unknown"); 291 292 debug_f("user %s authenticated by privileged process", authctxt->user); 293 ssh->authctxt = NULL; 294 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 295 296 mm_get_keystate(ssh, pmonitor); 297 298 /* Drain any buffered messages from the child */ 299 while (pmonitor->m_log_recvfd != -1 && monitor_read_log(pmonitor) == 0) 300 ; 301 302 if (pmonitor->m_recvfd >= 0) 303 close(pmonitor->m_recvfd); 304 if (pmonitor->m_log_sendfd >= 0) 305 close(pmonitor->m_log_sendfd); 306 pmonitor->m_sendfd = pmonitor->m_log_recvfd = -1; 307 } 308 309 static void 310 monitor_set_child_handler(pid_t pid) 311 { 312 monitor_child_pid = pid; 313 } 314 315 static void 316 monitor_child_handler(int sig) 317 { 318 kill(monitor_child_pid, sig); 319 } 320 321 void 322 monitor_child_postauth(struct ssh *ssh, struct monitor *pmonitor) 323 { 324 close(pmonitor->m_recvfd); 325 pmonitor->m_recvfd = -1; 326 327 monitor_set_child_handler(pmonitor->m_pid); 328 ssh_signal(SIGHUP, &monitor_child_handler); 329 ssh_signal(SIGTERM, &monitor_child_handler); 330 ssh_signal(SIGINT, &monitor_child_handler); 331 332 mon_dispatch = mon_dispatch_postauth20; 333 334 /* Permit requests for moduli and signatures */ 335 monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); 336 monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); 337 monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1); 338 339 if (auth_opts->permit_pty_flag) { 340 monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1); 341 monitor_permit(mon_dispatch, MONITOR_REQ_PTYCLEANUP, 1); 342 } 343 344 for (;;) 345 monitor_read(ssh, pmonitor, mon_dispatch, NULL); 346 } 347 348 static int 349 monitor_read_log(struct monitor *pmonitor) 350 { 351 struct sshbuf *logmsg; 352 u_int len, level, forced; 353 char *msg; 354 u_char *p; 355 int r; 356 357 if ((logmsg = sshbuf_new()) == NULL) 358 fatal_f("sshbuf_new"); 359 360 /* Read length */ 361 if ((r = sshbuf_reserve(logmsg, 4, &p)) != 0) 362 fatal_fr(r, "reserve len"); 363 if (atomicio(read, pmonitor->m_log_recvfd, p, 4) != 4) { 364 if (errno == EPIPE) { 365 sshbuf_free(logmsg); 366 debug_f("child log fd closed"); 367 close(pmonitor->m_log_recvfd); 368 pmonitor->m_log_recvfd = -1; 369 return -1; 370 } 371 fatal_f("log fd read: %s", strerror(errno)); 372 } 373 if ((r = sshbuf_get_u32(logmsg, &len)) != 0) 374 fatal_fr(r, "parse len"); 375 if (len <= 4 || len > 8192) 376 fatal_f("invalid log message length %u", len); 377 378 /* Read severity, message */ 379 sshbuf_reset(logmsg); 380 if ((r = sshbuf_reserve(logmsg, len, &p)) != 0) 381 fatal_fr(r, "reserve msg"); 382 if (atomicio(read, pmonitor->m_log_recvfd, p, len) != len) 383 fatal_f("log fd read: %s", strerror(errno)); 384 if ((r = sshbuf_get_u32(logmsg, &level)) != 0 || 385 (r = sshbuf_get_u32(logmsg, &forced)) != 0 || 386 (r = sshbuf_get_cstring(logmsg, &msg, NULL)) != 0) 387 fatal_fr(r, "parse"); 388 389 /* Log it */ 390 if (log_level_name(level) == NULL) 391 fatal_f("invalid log level %u (corrupted message?)", level); 392 sshlogdirect(level, forced, "%s [preauth]", msg); 393 394 sshbuf_free(logmsg); 395 free(msg); 396 397 return 0; 398 } 399 400 static int 401 monitor_read(struct ssh *ssh, struct monitor *pmonitor, struct mon_table *ent, 402 struct mon_table **pent) 403 { 404 struct sshbuf *m; 405 int r, ret; 406 u_char type; 407 struct pollfd pfd[2]; 408 409 for (;;) { 410 memset(&pfd, 0, sizeof(pfd)); 411 pfd[0].fd = pmonitor->m_sendfd; 412 pfd[0].events = POLLIN; 413 pfd[1].fd = pmonitor->m_log_recvfd; 414 pfd[1].events = pfd[1].fd == -1 ? 0 : POLLIN; 415 if (poll(pfd, pfd[1].fd == -1 ? 1 : 2, -1) == -1) { 416 if (errno == EINTR || errno == EAGAIN) 417 continue; 418 fatal_f("poll: %s", strerror(errno)); 419 } 420 if (pfd[1].revents) { 421 /* 422 * Drain all log messages before processing next 423 * monitor request. 424 */ 425 monitor_read_log(pmonitor); 426 continue; 427 } 428 if (pfd[0].revents) 429 break; /* Continues below */ 430 } 431 432 if ((m = sshbuf_new()) == NULL) 433 fatal_f("sshbuf_new"); 434 435 mm_request_receive(pmonitor->m_sendfd, m); 436 if ((r = sshbuf_get_u8(m, &type)) != 0) 437 fatal_fr(r, "parse type"); 438 439 debug3_f("checking request %d", type); 440 441 while (ent->f != NULL) { 442 if (ent->type == type) 443 break; 444 ent++; 445 } 446 447 if (ent->f != NULL) { 448 if (!(ent->flags & MON_PERMIT)) 449 fatal_f("unpermitted request %d", type); 450 ret = (*ent->f)(ssh, pmonitor->m_sendfd, m); 451 sshbuf_free(m); 452 453 /* The child may use this request only once, disable it */ 454 if (ent->flags & MON_ONCE) { 455 debug2_f("%d used once, disabling now", type); 456 ent->flags &= ~MON_PERMIT; 457 } 458 459 if (pent != NULL) 460 *pent = ent; 461 462 return ret; 463 } 464 465 fatal_f("unsupported request: %d", type); 466 467 /* NOTREACHED */ 468 return (-1); 469 } 470 471 /* allowed key state */ 472 static int 473 monitor_allowed_key(const u_char *blob, u_int bloblen) 474 { 475 /* make sure key is allowed */ 476 if (key_blob == NULL || key_bloblen != bloblen || 477 timingsafe_bcmp(key_blob, blob, key_bloblen)) 478 return (0); 479 return (1); 480 } 481 482 static void 483 monitor_reset_key_state(void) 484 { 485 /* reset state */ 486 free(key_blob); 487 free(hostbased_cuser); 488 free(hostbased_chost); 489 sshauthopt_free(key_opts); 490 key_blob = NULL; 491 key_bloblen = 0; 492 key_blobtype = MM_NOKEY; 493 key_opts = NULL; 494 hostbased_cuser = NULL; 495 hostbased_chost = NULL; 496 } 497 498 #ifdef WITH_OPENSSL 499 int 500 mm_answer_moduli(struct ssh *ssh, int sock, struct sshbuf *m) 501 { 502 DH *dh; 503 const BIGNUM *dh_p, *dh_g; 504 int r; 505 u_int min, want, max; 506 507 if ((r = sshbuf_get_u32(m, &min)) != 0 || 508 (r = sshbuf_get_u32(m, &want)) != 0 || 509 (r = sshbuf_get_u32(m, &max)) != 0) 510 fatal_fr(r, "parse"); 511 512 debug3_f("got parameters: %d %d %d", min, want, max); 513 /* We need to check here, too, in case the child got corrupted */ 514 if (max < min || want < min || max < want) 515 fatal_f("bad parameters: %d %d %d", min, want, max); 516 517 sshbuf_reset(m); 518 519 dh = choose_dh(min, want, max); 520 if (dh == NULL) { 521 if ((r = sshbuf_put_u8(m, 0)) != 0) 522 fatal_fr(r, "assemble empty"); 523 return (0); 524 } else { 525 /* Send first bignum */ 526 DH_get0_pqg(dh, &dh_p, NULL, &dh_g); 527 if ((r = sshbuf_put_u8(m, 1)) != 0 || 528 (r = sshbuf_put_bignum2(m, dh_p)) != 0 || 529 (r = sshbuf_put_bignum2(m, dh_g)) != 0) 530 fatal_fr(r, "assemble"); 531 532 DH_free(dh); 533 } 534 mm_request_send(sock, MONITOR_ANS_MODULI, m); 535 return (0); 536 } 537 #endif 538 539 int 540 mm_answer_sign(struct ssh *ssh, int sock, struct sshbuf *m) 541 { 542 extern int auth_sock; /* XXX move to state struct? */ 543 struct sshkey *key; 544 struct sshbuf *sigbuf = NULL; 545 u_char *p = NULL, *signature = NULL; 546 char *alg = NULL; 547 size_t datlen, siglen, alglen; 548 int r, is_proof = 0; 549 u_int keyid, compat; 550 const char proof_req[] = "hostkeys-prove-00@openssh.com"; 551 552 debug3_f("entering"); 553 554 if ((r = sshbuf_get_u32(m, &keyid)) != 0 || 555 (r = sshbuf_get_string(m, &p, &datlen)) != 0 || 556 (r = sshbuf_get_cstring(m, &alg, &alglen)) != 0 || 557 (r = sshbuf_get_u32(m, &compat)) != 0) 558 fatal_fr(r, "parse"); 559 if (keyid > INT_MAX) 560 fatal_f("invalid key ID"); 561 562 /* 563 * Supported KEX types use SHA1 (20 bytes), SHA256 (32 bytes), 564 * SHA384 (48 bytes) and SHA512 (64 bytes). 565 * 566 * Otherwise, verify the signature request is for a hostkey 567 * proof. 568 * 569 * XXX perform similar check for KEX signature requests too? 570 * it's not trivial, since what is signed is the hash, rather 571 * than the full kex structure... 572 */ 573 if (datlen != 20 && datlen != 32 && datlen != 48 && datlen != 64) { 574 /* 575 * Construct expected hostkey proof and compare it to what 576 * the client sent us. 577 */ 578 if (session_id2_len == 0) /* hostkeys is never first */ 579 fatal_f("bad data length: %zu", datlen); 580 if ((key = get_hostkey_public_by_index(keyid, ssh)) == NULL) 581 fatal_f("no hostkey for index %d", keyid); 582 if ((sigbuf = sshbuf_new()) == NULL) 583 fatal_f("sshbuf_new"); 584 if ((r = sshbuf_put_cstring(sigbuf, proof_req)) != 0 || 585 (r = sshbuf_put_string(sigbuf, session_id2, 586 session_id2_len)) != 0 || 587 (r = sshkey_puts(key, sigbuf)) != 0) 588 fatal_fr(r, "assemble private key proof"); 589 if (datlen != sshbuf_len(sigbuf) || 590 memcmp(p, sshbuf_ptr(sigbuf), sshbuf_len(sigbuf)) != 0) 591 fatal_f("bad data length: %zu, hostkey proof len %zu", 592 datlen, sshbuf_len(sigbuf)); 593 sshbuf_free(sigbuf); 594 is_proof = 1; 595 } 596 597 /* save session id, it will be passed on the first call */ 598 if (session_id2_len == 0) { 599 session_id2_len = datlen; 600 session_id2 = xmalloc(session_id2_len); 601 memcpy(session_id2, p, session_id2_len); 602 } 603 604 if ((key = get_hostkey_by_index(keyid)) != NULL) { 605 if ((r = sshkey_sign(key, &signature, &siglen, p, datlen, alg, 606 options.sk_provider, NULL, compat)) != 0) 607 fatal_fr(r, "sign"); 608 } else if ((key = get_hostkey_public_by_index(keyid, ssh)) != NULL && 609 auth_sock > 0) { 610 if ((r = ssh_agent_sign(auth_sock, key, &signature, &siglen, 611 p, datlen, alg, compat)) != 0) 612 fatal_fr(r, "agent sign"); 613 } else 614 fatal_f("no hostkey from index %d", keyid); 615 616 debug3_f("%s %s signature len=%zu", alg, 617 is_proof ? "hostkey proof" : "KEX", siglen); 618 619 sshbuf_reset(m); 620 if ((r = sshbuf_put_string(m, signature, siglen)) != 0) 621 fatal_fr(r, "assemble"); 622 623 free(alg); 624 free(p); 625 free(signature); 626 627 mm_request_send(sock, MONITOR_ANS_SIGN, m); 628 629 /* Turn on permissions for getpwnam */ 630 monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1); 631 632 return (0); 633 } 634 635 #define PUTPW(b, id) \ 636 do { \ 637 if ((r = sshbuf_put_string(b, \ 638 &pwent->id, sizeof(pwent->id))) != 0) \ 639 fatal_fr(r, "assemble %s", #id); \ 640 } while (0) 641 642 void 643 mm_encode_server_options(struct sshbuf *m) 644 { 645 int r; 646 u_int i; 647 648 /* XXX this leaks raw pointers to the unpriv child processes */ 649 if ((r = sshbuf_put_string(m, &options, sizeof(options))) != 0) 650 fatal_fr(r, "assemble options"); 651 652 #define M_CP_STROPT(x) do { \ 653 if (options.x != NULL && \ 654 (r = sshbuf_put_cstring(m, options.x)) != 0) \ 655 fatal_fr(r, "assemble %s", #x); \ 656 } while (0) 657 #define M_CP_STRARRAYOPT(x, nx) do { \ 658 for (i = 0; i < options.nx; i++) { \ 659 if ((r = sshbuf_put_cstring(m, options.x[i])) != 0) \ 660 fatal_fr(r, "assemble %s", #x); \ 661 } \ 662 } while (0) 663 /* See comment in servconf.h */ 664 COPY_MATCH_STRING_OPTS(); 665 #undef M_CP_STROPT 666 #undef M_CP_STRARRAYOPT 667 } 668 669 /* Retrieves the password entry and also checks if the user is permitted */ 670 int 671 mm_answer_pwnamallow(struct ssh *ssh, int sock, struct sshbuf *m) 672 { 673 struct passwd *pwent; 674 int r, allowed = 0; 675 676 debug3_f("entering"); 677 678 if (authctxt->attempt++ != 0) 679 fatal_f("multiple attempts for getpwnam"); 680 681 if ((r = sshbuf_get_cstring(m, &authctxt->user, NULL)) != 0) 682 fatal_fr(r, "parse"); 683 684 pwent = getpwnamallow(ssh, authctxt->user); 685 686 setproctitle("%s [priv]", pwent ? authctxt->user : "unknown"); 687 688 sshbuf_reset(m); 689 690 if (pwent == NULL) { 691 if ((r = sshbuf_put_u8(m, 0)) != 0) 692 fatal_fr(r, "assemble fakepw"); 693 authctxt->pw = fakepw(); 694 goto out; 695 } 696 697 allowed = 1; 698 authctxt->pw = pwent; 699 authctxt->valid = 1; 700 701 /* XXX send fake class/dir/shell, etc. */ 702 if ((r = sshbuf_put_u8(m, 1)) != 0) 703 fatal_fr(r, "assemble ok"); 704 PUTPW(m, pw_uid); 705 PUTPW(m, pw_gid); 706 PUTPW(m, pw_change); 707 PUTPW(m, pw_expire); 708 if ((r = sshbuf_put_cstring(m, pwent->pw_name)) != 0 || 709 (r = sshbuf_put_cstring(m, "*")) != 0 || 710 (r = sshbuf_put_cstring(m, pwent->pw_gecos)) != 0 || 711 (r = sshbuf_put_cstring(m, pwent->pw_class)) != 0 || 712 (r = sshbuf_put_cstring(m, pwent->pw_dir)) != 0 || 713 (r = sshbuf_put_cstring(m, pwent->pw_shell)) != 0) 714 fatal_fr(r, "assemble pw"); 715 716 out: 717 ssh_packet_set_log_preamble(ssh, "%suser %s", 718 authctxt->valid ? "authenticating" : "invalid ", authctxt->user); 719 720 /* Send active options to unpriv */ 721 mm_encode_server_options(m); 722 723 /* Create valid auth method lists */ 724 if (auth2_setup_methods_lists(authctxt) != 0) { 725 /* 726 * The monitor will continue long enough to let the child 727 * run to its packet_disconnect(), but it must not allow any 728 * authentication to succeed. 729 */ 730 debug_f("no valid authentication method lists"); 731 } 732 733 debug3_f("sending MONITOR_ANS_PWNAM: %d", allowed); 734 mm_request_send(sock, MONITOR_ANS_PWNAM, m); 735 736 /* Allow service/style information on the auth context */ 737 monitor_permit(mon_dispatch, MONITOR_REQ_AUTHSERV, 1); 738 monitor_permit(mon_dispatch, MONITOR_REQ_AUTH2_READ_BANNER, 1); 739 740 return (0); 741 } 742 743 int mm_answer_auth2_read_banner(struct ssh *ssh, int sock, struct sshbuf *m) 744 { 745 char *banner; 746 int r; 747 748 sshbuf_reset(m); 749 banner = auth2_read_banner(); 750 if ((r = sshbuf_put_cstring(m, banner != NULL ? banner : "")) != 0) 751 fatal_fr(r, "assemble"); 752 mm_request_send(sock, MONITOR_ANS_AUTH2_READ_BANNER, m); 753 free(banner); 754 755 return (0); 756 } 757 758 int 759 mm_answer_authserv(struct ssh *ssh, int sock, struct sshbuf *m) 760 { 761 int r; 762 763 monitor_permit_authentications(1); 764 765 if ((r = sshbuf_get_cstring(m, &authctxt->service, NULL)) != 0 || 766 (r = sshbuf_get_cstring(m, &authctxt->style, NULL)) != 0) 767 fatal_fr(r, "parse"); 768 debug3_f("service=%s, style=%s", authctxt->service, authctxt->style); 769 770 if (strlen(authctxt->style) == 0) { 771 free(authctxt->style); 772 authctxt->style = NULL; 773 } 774 775 return (0); 776 } 777 778 int 779 mm_answer_authpassword(struct ssh *ssh, int sock, struct sshbuf *m) 780 { 781 static int call_count; 782 char *passwd; 783 int r, authenticated; 784 size_t plen; 785 786 if (!options.password_authentication) 787 fatal_f("password authentication not enabled"); 788 if ((r = sshbuf_get_cstring(m, &passwd, &plen)) != 0) 789 fatal_fr(r, "parse"); 790 /* Only authenticate if the context is valid */ 791 authenticated = options.password_authentication && 792 auth_password(ssh, passwd); 793 freezero(passwd, plen); 794 795 sshbuf_reset(m); 796 if ((r = sshbuf_put_u32(m, authenticated)) != 0) 797 fatal_fr(r, "assemble"); 798 799 debug3_f("sending result %d", authenticated); 800 mm_request_send(sock, MONITOR_ANS_AUTHPASSWORD, m); 801 802 call_count++; 803 if (plen == 0 && call_count == 1) 804 auth_method = "none"; 805 else 806 auth_method = "password"; 807 808 /* Causes monitor loop to terminate if authenticated */ 809 return (authenticated); 810 } 811 812 int 813 mm_answer_bsdauthquery(struct ssh *ssh, int sock, struct sshbuf *m) 814 { 815 char *name, *infotxt; 816 u_int numprompts, *echo_on, success; 817 char **prompts; 818 int r; 819 820 if (!options.kbd_interactive_authentication) 821 fatal_f("kbd-int authentication not enabled"); 822 success = bsdauth_query(authctxt, &name, &infotxt, &numprompts, 823 &prompts, &echo_on) < 0 ? 0 : 1; 824 825 sshbuf_reset(m); 826 if ((r = sshbuf_put_u32(m, success)) != 0) 827 fatal_fr(r, "assemble"); 828 if (success) { 829 if ((r = sshbuf_put_cstring(m, prompts[0])) != 0) 830 fatal_fr(r, "assemble prompt"); 831 } 832 833 debug3_f("sending challenge success: %u", success); 834 mm_request_send(sock, MONITOR_ANS_BSDAUTHQUERY, m); 835 836 if (success) { 837 free(name); 838 free(infotxt); 839 free(prompts); 840 free(echo_on); 841 } 842 843 return (0); 844 } 845 846 int 847 mm_answer_bsdauthrespond(struct ssh *ssh, int sock, struct sshbuf *m) 848 { 849 char *response; 850 int r, authok; 851 852 if (!options.kbd_interactive_authentication) 853 fatal_f("kbd-int authentication not enabled"); 854 if (authctxt->as == NULL) 855 fatal_f("no bsd auth session"); 856 857 if ((r = sshbuf_get_cstring(m, &response, NULL)) != 0) 858 fatal_fr(r, "parse"); 859 authok = options.kbd_interactive_authentication && 860 auth_userresponse(authctxt->as, response, 0); 861 authctxt->as = NULL; 862 debug3_f("<%s> = <%d>", response, authok); 863 free(response); 864 865 sshbuf_reset(m); 866 if ((r = sshbuf_put_u32(m, authok)) != 0) 867 fatal_fr(r, "assemble"); 868 869 debug3_f("sending authenticated: %d", authok); 870 mm_request_send(sock, MONITOR_ANS_BSDAUTHRESPOND, m); 871 872 auth_method = "keyboard-interactive"; 873 auth_submethod = "bsdauth"; 874 875 return (authok != 0); 876 } 877 878 /* 879 * Check that the key type appears in the supplied pattern list, ignoring 880 * mismatches in the signature algorithm. (Signature algorithm checks are 881 * performed in the unprivileged authentication code). 882 * Returns 1 on success, 0 otherwise. 883 */ 884 static int 885 key_base_type_match(const char *method, const struct sshkey *key, 886 const char *list) 887 { 888 char *s, *l, *ol = xstrdup(list); 889 int found = 0; 890 891 l = ol; 892 for ((s = strsep(&l, ",")); s && *s != '\0'; (s = strsep(&l, ","))) { 893 if (sshkey_type_from_name(s) == key->type) { 894 found = 1; 895 break; 896 } 897 } 898 if (!found) { 899 error("%s key type %s is not in permitted list %s", method, 900 sshkey_ssh_name(key), list); 901 } 902 903 free(ol); 904 return found; 905 } 906 907 int 908 mm_answer_keyallowed(struct ssh *ssh, int sock, struct sshbuf *m) 909 { 910 struct sshkey *key = NULL; 911 char *cuser, *chost; 912 u_int pubkey_auth_attempt; 913 u_int type = 0; 914 int r, allowed = 0; 915 struct sshauthopt *opts = NULL; 916 917 debug3_f("entering"); 918 if ((r = sshbuf_get_u32(m, &type)) != 0 || 919 (r = sshbuf_get_cstring(m, &cuser, NULL)) != 0 || 920 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 || 921 (r = sshkey_froms(m, &key)) != 0 || 922 (r = sshbuf_get_u32(m, &pubkey_auth_attempt)) != 0) 923 fatal_fr(r, "parse"); 924 925 if (key != NULL && authctxt->valid) { 926 switch (type) { 927 case MM_USERKEY: 928 auth_method = "publickey"; 929 if (!options.pubkey_authentication) 930 break; 931 if (auth2_key_already_used(authctxt, key)) 932 break; 933 if (!key_base_type_match(auth_method, key, 934 options.pubkey_accepted_algos)) 935 break; 936 allowed = user_key_allowed(ssh, authctxt->pw, key, 937 pubkey_auth_attempt, &opts); 938 break; 939 case MM_HOSTKEY: 940 auth_method = "hostbased"; 941 if (!options.hostbased_authentication) 942 break; 943 if (auth2_key_already_used(authctxt, key)) 944 break; 945 if (!key_base_type_match(auth_method, key, 946 options.hostbased_accepted_algos)) 947 break; 948 allowed = hostbased_key_allowed(ssh, authctxt->pw, 949 cuser, chost, key); 950 auth2_record_info(authctxt, 951 "client user \"%.100s\", client host \"%.100s\"", 952 cuser, chost); 953 break; 954 default: 955 fatal_f("unknown key type %u", type); 956 break; 957 } 958 } 959 960 debug3_f("%s authentication%s: %s key is %s", auth_method, 961 pubkey_auth_attempt ? "" : " test", 962 (key == NULL || !authctxt->valid) ? "invalid" : sshkey_type(key), 963 allowed ? "allowed" : "not allowed"); 964 965 auth2_record_key(authctxt, 0, key); 966 967 /* clear temporarily storage (used by verify) */ 968 monitor_reset_key_state(); 969 970 if (allowed) { 971 /* Save temporarily for comparison in verify */ 972 if ((r = sshkey_to_blob(key, &key_blob, &key_bloblen)) != 0) 973 fatal_fr(r, "sshkey_to_blob"); 974 key_blobtype = type; 975 key_opts = opts; 976 hostbased_cuser = cuser; 977 hostbased_chost = chost; 978 } else { 979 /* Log failed attempt */ 980 auth_log(ssh, 0, 0, auth_method, NULL); 981 free(cuser); 982 free(chost); 983 } 984 sshkey_free(key); 985 986 sshbuf_reset(m); 987 if ((r = sshbuf_put_u32(m, allowed)) != 0) 988 fatal_fr(r, "assemble"); 989 if (opts != NULL && (r = sshauthopt_serialise(opts, m, 1)) != 0) 990 fatal_fr(r, "sshauthopt_serialise"); 991 mm_request_send(sock, MONITOR_ANS_KEYALLOWED, m); 992 993 if (!allowed) 994 sshauthopt_free(opts); 995 996 return (0); 997 } 998 999 static int 1000 monitor_valid_userblob(struct ssh *ssh, const u_char *data, u_int datalen) 1001 { 1002 struct sshbuf *b; 1003 struct sshkey *hostkey = NULL; 1004 const u_char *p; 1005 char *userstyle, *cp; 1006 size_t len; 1007 u_char type; 1008 int hostbound = 0, r, fail = 0; 1009 1010 if ((b = sshbuf_from(data, datalen)) == NULL) 1011 fatal_f("sshbuf_from"); 1012 1013 if (ssh->compat & SSH_OLD_SESSIONID) { 1014 p = sshbuf_ptr(b); 1015 len = sshbuf_len(b); 1016 if ((session_id2 == NULL) || 1017 (len < session_id2_len) || 1018 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) 1019 fail++; 1020 if ((r = sshbuf_consume(b, session_id2_len)) != 0) 1021 fatal_fr(r, "consume"); 1022 } else { 1023 if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0) 1024 fatal_fr(r, "parse sessionid"); 1025 if ((session_id2 == NULL) || 1026 (len != session_id2_len) || 1027 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) 1028 fail++; 1029 } 1030 if ((r = sshbuf_get_u8(b, &type)) != 0) 1031 fatal_fr(r, "parse type"); 1032 if (type != SSH2_MSG_USERAUTH_REQUEST) 1033 fail++; 1034 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1035 fatal_fr(r, "parse userstyle"); 1036 xasprintf(&userstyle, "%s%s%s", authctxt->user, 1037 authctxt->style ? ":" : "", 1038 authctxt->style ? authctxt->style : ""); 1039 if (strcmp(userstyle, cp) != 0) { 1040 logit("wrong user name passed to monitor: " 1041 "expected %s != %.100s", userstyle, cp); 1042 fail++; 1043 } 1044 free(userstyle); 1045 free(cp); 1046 if ((r = sshbuf_skip_string(b)) != 0 || /* service */ 1047 (r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1048 fatal_fr(r, "parse method"); 1049 if (strcmp("publickey", cp) != 0) { 1050 if (strcmp("publickey-hostbound-v00@openssh.com", cp) == 0) 1051 hostbound = 1; 1052 else 1053 fail++; 1054 } 1055 free(cp); 1056 if ((r = sshbuf_get_u8(b, &type)) != 0) 1057 fatal_fr(r, "parse pktype"); 1058 if (type == 0) 1059 fail++; 1060 if ((r = sshbuf_skip_string(b)) != 0 || /* pkalg */ 1061 (r = sshbuf_skip_string(b)) != 0 || /* pkblob */ 1062 (hostbound && (r = sshkey_froms(b, &hostkey)) != 0)) 1063 fatal_fr(r, "parse pk"); 1064 if (sshbuf_len(b) != 0) 1065 fail++; 1066 sshbuf_free(b); 1067 if (hostkey != NULL) { 1068 /* 1069 * Ensure this is actually one of our hostkeys; unfortunately 1070 * can't check ssh->kex->initial_hostkey directly at this point 1071 * as packet state has not yet been exported to monitor. 1072 */ 1073 if (get_hostkey_index(hostkey, 1, ssh) == -1) 1074 fatal_f("hostbound hostkey does not match"); 1075 sshkey_free(hostkey); 1076 } 1077 return (fail == 0); 1078 } 1079 1080 static int 1081 monitor_valid_hostbasedblob(const u_char *data, u_int datalen, 1082 const char *cuser, const char *chost) 1083 { 1084 struct sshbuf *b; 1085 const u_char *p; 1086 char *cp, *userstyle; 1087 size_t len; 1088 int r, fail = 0; 1089 u_char type; 1090 1091 if ((b = sshbuf_from(data, datalen)) == NULL) 1092 fatal_f("sshbuf_new"); 1093 if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0) 1094 fatal_fr(r, "parse sessionid"); 1095 1096 if ((session_id2 == NULL) || 1097 (len != session_id2_len) || 1098 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) 1099 fail++; 1100 1101 if ((r = sshbuf_get_u8(b, &type)) != 0) 1102 fatal_fr(r, "parse type"); 1103 if (type != SSH2_MSG_USERAUTH_REQUEST) 1104 fail++; 1105 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1106 fatal_fr(r, "parse userstyle"); 1107 xasprintf(&userstyle, "%s%s%s", authctxt->user, 1108 authctxt->style ? ":" : "", 1109 authctxt->style ? authctxt->style : ""); 1110 if (strcmp(userstyle, cp) != 0) { 1111 logit("wrong user name passed to monitor: " 1112 "expected %s != %.100s", userstyle, cp); 1113 fail++; 1114 } 1115 free(userstyle); 1116 free(cp); 1117 if ((r = sshbuf_skip_string(b)) != 0 || /* service */ 1118 (r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1119 fatal_fr(r, "parse method"); 1120 if (strcmp(cp, "hostbased") != 0) 1121 fail++; 1122 free(cp); 1123 if ((r = sshbuf_skip_string(b)) != 0 || /* pkalg */ 1124 (r = sshbuf_skip_string(b)) != 0) /* pkblob */ 1125 fatal_fr(r, "parse pk"); 1126 1127 /* verify client host, strip trailing dot if necessary */ 1128 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1129 fatal_fr(r, "parse host"); 1130 if (((len = strlen(cp)) > 0) && cp[len - 1] == '.') 1131 cp[len - 1] = '\0'; 1132 if (strcmp(cp, chost) != 0) 1133 fail++; 1134 free(cp); 1135 1136 /* verify client user */ 1137 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1138 fatal_fr(r, "parse ruser"); 1139 if (strcmp(cp, cuser) != 0) 1140 fail++; 1141 free(cp); 1142 1143 if (sshbuf_len(b) != 0) 1144 fail++; 1145 sshbuf_free(b); 1146 return (fail == 0); 1147 } 1148 1149 int 1150 mm_answer_keyverify(struct ssh *ssh, int sock, struct sshbuf *m) 1151 { 1152 struct sshkey *key; 1153 const u_char *signature, *data, *blob; 1154 char *sigalg = NULL, *fp = NULL; 1155 size_t signaturelen, datalen, bloblen; 1156 int r, ret, req_presence = 0, req_verify = 0, valid_data = 0; 1157 int encoded_ret; 1158 struct sshkey_sig_details *sig_details = NULL; 1159 1160 if ((r = sshbuf_get_string_direct(m, &blob, &bloblen)) != 0 || 1161 (r = sshbuf_get_string_direct(m, &signature, &signaturelen)) != 0 || 1162 (r = sshbuf_get_string_direct(m, &data, &datalen)) != 0 || 1163 (r = sshbuf_get_cstring(m, &sigalg, NULL)) != 0) 1164 fatal_fr(r, "parse"); 1165 1166 if (hostbased_cuser == NULL || hostbased_chost == NULL || 1167 !monitor_allowed_key(blob, bloblen)) 1168 fatal_f("bad key, not previously allowed"); 1169 1170 /* Empty signature algorithm means NULL. */ 1171 if (*sigalg == '\0') { 1172 free(sigalg); 1173 sigalg = NULL; 1174 } 1175 1176 /* XXX use sshkey_froms here; need to change key_blob, etc. */ 1177 if ((r = sshkey_from_blob(blob, bloblen, &key)) != 0) 1178 fatal_fr(r, "parse key"); 1179 1180 switch (key_blobtype) { 1181 case MM_USERKEY: 1182 valid_data = monitor_valid_userblob(ssh, data, datalen); 1183 auth_method = "publickey"; 1184 break; 1185 case MM_HOSTKEY: 1186 valid_data = monitor_valid_hostbasedblob(data, datalen, 1187 hostbased_cuser, hostbased_chost); 1188 auth_method = "hostbased"; 1189 break; 1190 default: 1191 valid_data = 0; 1192 break; 1193 } 1194 if (!valid_data) 1195 fatal_f("bad %s signature data blob", 1196 key_blobtype == MM_USERKEY ? "userkey" : 1197 (key_blobtype == MM_HOSTKEY ? "hostkey" : "unknown")); 1198 1199 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, 1200 SSH_FP_DEFAULT)) == NULL) 1201 fatal_f("sshkey_fingerprint failed"); 1202 1203 ret = sshkey_verify(key, signature, signaturelen, data, datalen, 1204 sigalg, ssh->compat, &sig_details); 1205 debug3_f("%s %s signature using %s %s%s%s", auth_method, 1206 sshkey_type(key), sigalg == NULL ? "default" : sigalg, 1207 (ret == 0) ? "verified" : "unverified", 1208 (ret != 0) ? ": " : "", (ret != 0) ? ssh_err(ret) : ""); 1209 1210 if (ret == 0 && key_blobtype == MM_USERKEY && sig_details != NULL) { 1211 req_presence = (options.pubkey_auth_options & 1212 PUBKEYAUTH_TOUCH_REQUIRED) || 1213 !key_opts->no_require_user_presence; 1214 if (req_presence && 1215 (sig_details->sk_flags & SSH_SK_USER_PRESENCE_REQD) == 0) { 1216 error("public key %s %s signature for %s%s from %.128s " 1217 "port %d rejected: user presence " 1218 "(authenticator touch) requirement not met ", 1219 sshkey_type(key), fp, 1220 authctxt->valid ? "" : "invalid user ", 1221 authctxt->user, ssh_remote_ipaddr(ssh), 1222 ssh_remote_port(ssh)); 1223 ret = SSH_ERR_SIGNATURE_INVALID; 1224 } 1225 req_verify = (options.pubkey_auth_options & 1226 PUBKEYAUTH_VERIFY_REQUIRED) || key_opts->require_verify; 1227 if (req_verify && 1228 (sig_details->sk_flags & SSH_SK_USER_VERIFICATION_REQD) == 0) { 1229 error("public key %s %s signature for %s%s from %.128s " 1230 "port %d rejected: user verification requirement " 1231 "not met ", sshkey_type(key), fp, 1232 authctxt->valid ? "" : "invalid user ", 1233 authctxt->user, ssh_remote_ipaddr(ssh), 1234 ssh_remote_port(ssh)); 1235 ret = SSH_ERR_SIGNATURE_INVALID; 1236 } 1237 } 1238 auth2_record_key(authctxt, ret == 0, key); 1239 1240 if (key_blobtype == MM_USERKEY) 1241 auth_activate_options(ssh, key_opts); 1242 monitor_reset_key_state(); 1243 1244 sshbuf_reset(m); 1245 1246 /* encode ret != 0 as positive integer, since we're sending u32 */ 1247 encoded_ret = (ret != 0); 1248 if ((r = sshbuf_put_u32(m, encoded_ret)) != 0 || 1249 (r = sshbuf_put_u8(m, sig_details != NULL)) != 0) 1250 fatal_fr(r, "assemble"); 1251 if (sig_details != NULL) { 1252 if ((r = sshbuf_put_u32(m, sig_details->sk_counter)) != 0 || 1253 (r = sshbuf_put_u8(m, sig_details->sk_flags)) != 0) 1254 fatal_fr(r, "assemble sk"); 1255 } 1256 sshkey_sig_details_free(sig_details); 1257 mm_request_send(sock, MONITOR_ANS_KEYVERIFY, m); 1258 1259 free(sigalg); 1260 free(fp); 1261 sshkey_free(key); 1262 1263 return ret == 0; 1264 } 1265 1266 static void 1267 mm_record_login(struct ssh *ssh, Session *s, struct passwd *pw) 1268 { 1269 socklen_t fromlen; 1270 struct sockaddr_storage from; 1271 1272 /* 1273 * Get IP address of client. If the connection is not a socket, let 1274 * the address be 0.0.0.0. 1275 */ 1276 memset(&from, 0, sizeof(from)); 1277 fromlen = sizeof(from); 1278 if (ssh_packet_connection_is_on_socket(ssh)) { 1279 if (getpeername(ssh_packet_get_connection_in(ssh), 1280 (struct sockaddr *)&from, &fromlen) == -1) { 1281 debug("getpeername: %.100s", strerror(errno)); 1282 cleanup_exit(255); 1283 } 1284 } 1285 /* Record that there was a login on that tty from the remote host. */ 1286 record_login(s->pid, s->tty, pw->pw_name, pw->pw_uid, 1287 session_get_remote_name_or_ip(ssh, utmp_len, options.use_dns), 1288 (struct sockaddr *)&from, fromlen); 1289 } 1290 1291 static void 1292 mm_session_close(Session *s) 1293 { 1294 debug3_f("session %d pid %ld", s->self, (long)s->pid); 1295 if (s->ttyfd != -1) { 1296 debug3_f("tty %s ptyfd %d", s->tty, s->ptyfd); 1297 session_pty_cleanup2(s); 1298 } 1299 session_unused(s->self); 1300 } 1301 1302 int 1303 mm_answer_pty(struct ssh *ssh, int sock, struct sshbuf *m) 1304 { 1305 extern struct monitor *pmonitor; 1306 Session *s; 1307 int r, res, fd0; 1308 1309 debug3_f("entering"); 1310 1311 sshbuf_reset(m); 1312 s = session_new(); 1313 if (s == NULL) 1314 goto error; 1315 s->authctxt = authctxt; 1316 s->pw = authctxt->pw; 1317 s->pid = pmonitor->m_pid; 1318 res = pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty)); 1319 if (res == 0) 1320 goto error; 1321 pty_setowner(authctxt->pw, s->tty); 1322 1323 if ((r = sshbuf_put_u32(m, 1)) != 0 || 1324 (r = sshbuf_put_cstring(m, s->tty)) != 0) 1325 fatal_fr(r, "assemble"); 1326 1327 /* We need to trick ttyslot */ 1328 if (dup2(s->ttyfd, 0) == -1) 1329 fatal_f("dup2"); 1330 1331 mm_record_login(ssh, s, authctxt->pw); 1332 1333 /* Now we can close the file descriptor again */ 1334 close(0); 1335 1336 /* send messages generated by record_login */ 1337 if ((r = sshbuf_put_stringb(m, loginmsg)) != 0) 1338 fatal_fr(r, "assemble loginmsg"); 1339 sshbuf_reset(loginmsg); 1340 1341 mm_request_send(sock, MONITOR_ANS_PTY, m); 1342 1343 if (mm_send_fd(sock, s->ptyfd) == -1 || 1344 mm_send_fd(sock, s->ttyfd) == -1) 1345 fatal_f("send fds failed"); 1346 1347 /* make sure nothing uses fd 0 */ 1348 if ((fd0 = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1349 fatal_f("open(/dev/null): %s", strerror(errno)); 1350 if (fd0 != 0) 1351 error_f("fd0 %d != 0", fd0); 1352 1353 /* slave side of pty is not needed */ 1354 close(s->ttyfd); 1355 s->ttyfd = s->ptyfd; 1356 /* no need to dup() because nobody closes ptyfd */ 1357 s->ptymaster = s->ptyfd; 1358 1359 debug3_f("tty %s ptyfd %d", s->tty, s->ttyfd); 1360 1361 return (0); 1362 1363 error: 1364 if (s != NULL) 1365 mm_session_close(s); 1366 if ((r = sshbuf_put_u32(m, 0)) != 0) 1367 fatal_fr(r, "assemble 0"); 1368 mm_request_send(sock, MONITOR_ANS_PTY, m); 1369 return (0); 1370 } 1371 1372 int 1373 mm_answer_pty_cleanup(struct ssh *ssh, int sock, struct sshbuf *m) 1374 { 1375 Session *s; 1376 char *tty; 1377 int r; 1378 1379 debug3_f("entering"); 1380 1381 if ((r = sshbuf_get_cstring(m, &tty, NULL)) != 0) 1382 fatal_fr(r, "parse tty"); 1383 if ((s = session_by_tty(tty)) != NULL) 1384 mm_session_close(s); 1385 sshbuf_reset(m); 1386 free(tty); 1387 return (0); 1388 } 1389 1390 int 1391 mm_answer_term(struct ssh *ssh, int sock, struct sshbuf *req) 1392 { 1393 extern struct monitor *pmonitor; 1394 int res, status; 1395 1396 debug3_f("tearing down sessions"); 1397 1398 /* The child is terminating */ 1399 session_destroy_all(ssh, &mm_session_close); 1400 1401 while (waitpid(pmonitor->m_pid, &status, 0) == -1) 1402 if (errno != EINTR) 1403 exit(1); 1404 1405 res = WIFEXITED(status) ? WEXITSTATUS(status) : 1; 1406 1407 /* Terminate process */ 1408 exit(res); 1409 } 1410 1411 void 1412 monitor_clear_keystate(struct ssh *ssh, struct monitor *pmonitor) 1413 { 1414 ssh_clear_newkeys(ssh, MODE_IN); 1415 ssh_clear_newkeys(ssh, MODE_OUT); 1416 sshbuf_free(child_state); 1417 child_state = NULL; 1418 } 1419 1420 void 1421 monitor_apply_keystate(struct ssh *ssh, struct monitor *pmonitor) 1422 { 1423 struct kex *kex; 1424 int r; 1425 1426 debug3_f("packet_set_state"); 1427 if ((r = ssh_packet_set_state(ssh, child_state)) != 0) 1428 fatal_fr(r, "packet_set_state"); 1429 sshbuf_free(child_state); 1430 child_state = NULL; 1431 if ((kex = ssh->kex) == NULL) 1432 fatal_f("internal error: ssh->kex == NULL"); 1433 if (session_id2_len != sshbuf_len(ssh->kex->session_id)) { 1434 fatal_f("incorrect session id length %zu (expected %u)", 1435 sshbuf_len(ssh->kex->session_id), session_id2_len); 1436 } 1437 if (memcmp(sshbuf_ptr(ssh->kex->session_id), session_id2, 1438 session_id2_len) != 0) 1439 fatal_f("session ID mismatch"); 1440 /* XXX set callbacks */ 1441 #ifdef WITH_OPENSSL 1442 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server; 1443 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server; 1444 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server; 1445 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server; 1446 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server; 1447 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 1448 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 1449 kex->kex[KEX_ECDH_SHA2] = kex_gen_server; 1450 #endif 1451 kex->kex[KEX_C25519_SHA256] = kex_gen_server; 1452 kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server; 1453 kex->load_host_public_key=&get_hostkey_public_by_type; 1454 kex->load_host_private_key=&get_hostkey_private_by_type; 1455 kex->host_key_index=&get_hostkey_index; 1456 kex->sign = sshd_hostkey_sign; 1457 } 1458 1459 /* This function requires careful sanity checking */ 1460 1461 void 1462 mm_get_keystate(struct ssh *ssh, struct monitor *pmonitor) 1463 { 1464 debug3_f("Waiting for new keys"); 1465 1466 if ((child_state = sshbuf_new()) == NULL) 1467 fatal_f("sshbuf_new failed"); 1468 mm_request_receive_expect(pmonitor->m_sendfd, MONITOR_REQ_KEYEXPORT, 1469 child_state); 1470 debug3_f("GOT new keys"); 1471 } 1472 1473 1474 /* XXX */ 1475 1476 #define FD_CLOSEONEXEC(x) do { \ 1477 if (fcntl(x, F_SETFD, FD_CLOEXEC) == -1) \ 1478 fatal("fcntl(%d, F_SETFD)", x); \ 1479 } while (0) 1480 1481 static void 1482 monitor_openfds(struct monitor *mon, int do_logfds) 1483 { 1484 int pair[2]; 1485 #ifdef SO_ZEROIZE 1486 int on = 1; 1487 #endif 1488 1489 if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) 1490 fatal_f("socketpair: %s", strerror(errno)); 1491 #ifdef SO_ZEROIZE 1492 if (setsockopt(pair[0], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1) 1493 error("setsockopt SO_ZEROIZE(0): %.100s", strerror(errno)); 1494 if (setsockopt(pair[1], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1) 1495 error("setsockopt SO_ZEROIZE(1): %.100s", strerror(errno)); 1496 #endif 1497 FD_CLOSEONEXEC(pair[0]); 1498 FD_CLOSEONEXEC(pair[1]); 1499 mon->m_recvfd = pair[0]; 1500 mon->m_sendfd = pair[1]; 1501 1502 if (do_logfds) { 1503 if (pipe(pair) == -1) 1504 fatal_f("pipe: %s", strerror(errno)); 1505 FD_CLOSEONEXEC(pair[0]); 1506 FD_CLOSEONEXEC(pair[1]); 1507 mon->m_log_recvfd = pair[0]; 1508 mon->m_log_sendfd = pair[1]; 1509 } else 1510 mon->m_log_recvfd = mon->m_log_sendfd = -1; 1511 } 1512 1513 #define MM_MEMSIZE 65536 1514 1515 struct monitor * 1516 monitor_init(void) 1517 { 1518 struct monitor *mon; 1519 1520 mon = xcalloc(1, sizeof(*mon)); 1521 monitor_openfds(mon, 1); 1522 1523 return mon; 1524 } 1525 1526 void 1527 monitor_reinit(struct monitor *mon) 1528 { 1529 monitor_openfds(mon, 0); 1530 } 1531 1532 #ifdef GSSAPI 1533 int 1534 mm_answer_gss_setup_ctx(struct ssh *ssh, int sock, struct sshbuf *m) 1535 { 1536 gss_OID_desc goid; 1537 OM_uint32 major; 1538 size_t len; 1539 u_char *p; 1540 int r; 1541 1542 if (!options.gss_authentication) 1543 fatal_f("GSSAPI authentication not enabled"); 1544 1545 if ((r = sshbuf_get_string(m, &p, &len)) != 0) 1546 fatal_fr(r, "parse"); 1547 goid.elements = p; 1548 goid.length = len; 1549 1550 major = ssh_gssapi_server_ctx(&gsscontext, &goid); 1551 1552 free(goid.elements); 1553 1554 sshbuf_reset(m); 1555 if ((r = sshbuf_put_u32(m, major)) != 0) 1556 fatal_fr(r, "assemble"); 1557 1558 mm_request_send(sock, MONITOR_ANS_GSSSETUP, m); 1559 1560 /* Now we have a context, enable the step */ 1561 monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 1); 1562 1563 return (0); 1564 } 1565 1566 int 1567 mm_answer_gss_accept_ctx(struct ssh *ssh, int sock, struct sshbuf *m) 1568 { 1569 gss_buffer_desc in; 1570 gss_buffer_desc out = GSS_C_EMPTY_BUFFER; 1571 OM_uint32 major, minor; 1572 OM_uint32 flags = 0; /* GSI needs this */ 1573 int r; 1574 1575 if (!options.gss_authentication) 1576 fatal_f("GSSAPI authentication not enabled"); 1577 1578 if ((r = ssh_gssapi_get_buffer_desc(m, &in)) != 0) 1579 fatal_fr(r, "ssh_gssapi_get_buffer_desc"); 1580 major = ssh_gssapi_accept_ctx(gsscontext, &in, &out, &flags); 1581 free(in.value); 1582 1583 sshbuf_reset(m); 1584 if ((r = sshbuf_put_u32(m, major)) != 0 || 1585 (r = sshbuf_put_string(m, out.value, out.length)) != 0 || 1586 (r = sshbuf_put_u32(m, flags)) != 0) 1587 fatal_fr(r, "assemble"); 1588 mm_request_send(sock, MONITOR_ANS_GSSSTEP, m); 1589 1590 gss_release_buffer(&minor, &out); 1591 1592 if (major == GSS_S_COMPLETE) { 1593 monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 0); 1594 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1); 1595 monitor_permit(mon_dispatch, MONITOR_REQ_GSSCHECKMIC, 1); 1596 } 1597 return (0); 1598 } 1599 1600 int 1601 mm_answer_gss_checkmic(struct ssh *ssh, int sock, struct sshbuf *m) 1602 { 1603 gss_buffer_desc gssbuf, mic; 1604 OM_uint32 ret; 1605 int r; 1606 1607 if (!options.gss_authentication) 1608 fatal_f("GSSAPI authentication not enabled"); 1609 1610 if ((r = ssh_gssapi_get_buffer_desc(m, &gssbuf)) != 0 || 1611 (r = ssh_gssapi_get_buffer_desc(m, &mic)) != 0) 1612 fatal_fr(r, "ssh_gssapi_get_buffer_desc"); 1613 1614 ret = ssh_gssapi_checkmic(gsscontext, &gssbuf, &mic); 1615 1616 free(gssbuf.value); 1617 free(mic.value); 1618 1619 sshbuf_reset(m); 1620 if ((r = sshbuf_put_u32(m, ret)) != 0) 1621 fatal_fr(r, "assemble"); 1622 1623 mm_request_send(sock, MONITOR_ANS_GSSCHECKMIC, m); 1624 1625 if (!GSS_ERROR(ret)) 1626 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1); 1627 1628 return (0); 1629 } 1630 1631 int 1632 mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m) 1633 { 1634 int r, authenticated; 1635 const char *displayname; 1636 1637 if (!options.gss_authentication) 1638 fatal_f("GSSAPI authentication not enabled"); 1639 1640 authenticated = authctxt->valid && ssh_gssapi_userok(authctxt->user); 1641 1642 sshbuf_reset(m); 1643 if ((r = sshbuf_put_u32(m, authenticated)) != 0) 1644 fatal_fr(r, "assemble"); 1645 1646 debug3_f("sending result %d", authenticated); 1647 mm_request_send(sock, MONITOR_ANS_GSSUSEROK, m); 1648 1649 auth_method = "gssapi-with-mic"; 1650 1651 if ((displayname = ssh_gssapi_displayname()) != NULL) 1652 auth2_record_info(authctxt, "%s", displayname); 1653 1654 /* Monitor loop will terminate if authenticated */ 1655 return (authenticated); 1656 } 1657 #endif /* GSSAPI */ 1658 1659