1 /* $OpenBSD: monitor.c,v 1.223 2021/01/27 10:05:28 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 <sys/types.h> 29 #include <sys/wait.h> 30 #include <sys/socket.h> 31 #include <sys/tree.h> 32 #include <sys/queue.h> 33 34 #ifdef WITH_OPENSSL 35 #include <openssl/dh.h> 36 #endif 37 38 #include <errno.h> 39 #include <fcntl.h> 40 #include <limits.h> 41 #include <paths.h> 42 #include <poll.h> 43 #include <pwd.h> 44 #include <signal.h> 45 #include <stdarg.h> 46 #include <stdint.h> 47 #include <stdio.h> 48 #include <stdlib.h> 49 #include <string.h> 50 #include <unistd.h> 51 52 #include "atomicio.h" 53 #include "xmalloc.h" 54 #include "ssh.h" 55 #include "sshkey.h" 56 #include "sshbuf.h" 57 #include "hostfile.h" 58 #include "auth.h" 59 #include "cipher.h" 60 #include "kex.h" 61 #include "dh.h" 62 #include "packet.h" 63 #include "auth-options.h" 64 #include "sshpty.h" 65 #include "channels.h" 66 #include "session.h" 67 #include "sshlogin.h" 68 #include "canohost.h" 69 #include "log.h" 70 #include "misc.h" 71 #include "servconf.h" 72 #include "monitor.h" 73 #ifdef GSSAPI 74 #include "ssh-gss.h" 75 #endif 76 #include "monitor_wrap.h" 77 #include "monitor_fdpass.h" 78 #include "compat.h" 79 #include "ssh2.h" 80 #include "authfd.h" 81 #include "match.h" 82 #include "ssherr.h" 83 #include "sk-api.h" 84 85 #ifdef GSSAPI 86 static Gssctxt *gsscontext = NULL; 87 #endif 88 89 /* Imports */ 90 extern ServerOptions options; 91 extern u_int utmp_len; 92 extern struct sshbuf *loginmsg; 93 extern struct sshauthopt *auth_opts; /* XXX move to permanent ssh->authctxt? */ 94 95 /* State exported from the child */ 96 static struct sshbuf *child_state; 97 98 /* Functions on the monitor that answer unprivileged requests */ 99 100 int mm_answer_moduli(struct ssh *, int, struct sshbuf *); 101 int mm_answer_sign(struct ssh *, int, struct sshbuf *); 102 int mm_answer_pwnamallow(struct ssh *, int, struct sshbuf *); 103 int mm_answer_auth2_read_banner(struct ssh *, int, struct sshbuf *); 104 int mm_answer_authserv(struct ssh *, int, struct sshbuf *); 105 int mm_answer_authpassword(struct ssh *, int, struct sshbuf *); 106 int mm_answer_bsdauthquery(struct ssh *, int, struct sshbuf *); 107 int mm_answer_bsdauthrespond(struct ssh *, int, struct sshbuf *); 108 int mm_answer_skeyquery(struct ssh *, int, struct sshbuf *); 109 int mm_answer_skeyrespond(struct ssh *, int, struct sshbuf *); 110 int mm_answer_keyallowed(struct ssh *, int, struct sshbuf *); 111 int mm_answer_keyverify(struct ssh *, int, struct sshbuf *); 112 int mm_answer_pty(struct ssh *, int, struct sshbuf *); 113 int mm_answer_pty_cleanup(struct ssh *, int, struct sshbuf *); 114 int mm_answer_term(struct ssh *, int, struct sshbuf *); 115 int mm_answer_rsa_keyallowed(struct ssh *, int, struct sshbuf *); 116 int mm_answer_rsa_challenge(struct ssh *, int, struct sshbuf *); 117 int mm_answer_rsa_response(struct ssh *, int, struct sshbuf *); 118 int mm_answer_sesskey(struct ssh *, int, struct sshbuf *); 119 int mm_answer_sessid(struct ssh *, int, struct sshbuf *); 120 121 #ifdef GSSAPI 122 int mm_answer_gss_setup_ctx(struct ssh *, int, struct sshbuf *); 123 int mm_answer_gss_accept_ctx(struct ssh *, int, struct sshbuf *); 124 int mm_answer_gss_userok(struct ssh *, int, struct sshbuf *); 125 int mm_answer_gss_checkmic(struct ssh *, int, struct sshbuf *); 126 #endif 127 128 static Authctxt *authctxt; 129 130 /* local state for key verify */ 131 static u_char *key_blob = NULL; 132 static size_t key_bloblen = 0; 133 static int key_blobtype = MM_NOKEY; 134 static struct sshauthopt *key_opts = NULL; 135 static char *hostbased_cuser = NULL; 136 static char *hostbased_chost = NULL; 137 static char *auth_method = "unknown"; 138 static char *auth_submethod = NULL; 139 static u_int session_id2_len = 0; 140 static u_char *session_id2 = NULL; 141 static pid_t monitor_child_pid; 142 143 struct mon_table { 144 enum monitor_reqtype type; 145 int flags; 146 int (*f)(struct ssh *, int, struct sshbuf *); 147 }; 148 149 #define MON_ISAUTH 0x0004 /* Required for Authentication */ 150 #define MON_AUTHDECIDE 0x0008 /* Decides Authentication */ 151 #define MON_ONCE 0x0010 /* Disable after calling */ 152 #define MON_ALOG 0x0020 /* Log auth attempt without authenticating */ 153 154 #define MON_AUTH (MON_ISAUTH|MON_AUTHDECIDE) 155 156 #define MON_PERMIT 0x1000 /* Request is permitted */ 157 158 static int monitor_read(struct ssh *, struct monitor *, struct mon_table *, 159 struct mon_table **); 160 static int monitor_read_log(struct monitor *); 161 162 struct mon_table mon_dispatch_proto20[] = { 163 #ifdef WITH_OPENSSL 164 {MONITOR_REQ_MODULI, MON_ONCE, mm_answer_moduli}, 165 #endif 166 {MONITOR_REQ_SIGN, MON_ONCE, mm_answer_sign}, 167 {MONITOR_REQ_PWNAM, MON_ONCE, mm_answer_pwnamallow}, 168 {MONITOR_REQ_AUTHSERV, MON_ONCE, mm_answer_authserv}, 169 {MONITOR_REQ_AUTH2_READ_BANNER, MON_ONCE, mm_answer_auth2_read_banner}, 170 {MONITOR_REQ_AUTHPASSWORD, MON_AUTH, mm_answer_authpassword}, 171 {MONITOR_REQ_BSDAUTHQUERY, MON_ISAUTH, mm_answer_bsdauthquery}, 172 {MONITOR_REQ_BSDAUTHRESPOND, MON_AUTH, mm_answer_bsdauthrespond}, 173 {MONITOR_REQ_KEYALLOWED, MON_ISAUTH, mm_answer_keyallowed}, 174 {MONITOR_REQ_KEYVERIFY, MON_AUTH, mm_answer_keyverify}, 175 #ifdef GSSAPI 176 {MONITOR_REQ_GSSSETUP, MON_ISAUTH, mm_answer_gss_setup_ctx}, 177 {MONITOR_REQ_GSSSTEP, 0, mm_answer_gss_accept_ctx}, 178 {MONITOR_REQ_GSSUSEROK, MON_ONCE|MON_AUTHDECIDE, mm_answer_gss_userok}, 179 {MONITOR_REQ_GSSCHECKMIC, MON_ONCE, mm_answer_gss_checkmic}, 180 #endif 181 {0, 0, NULL} 182 }; 183 184 struct mon_table mon_dispatch_postauth20[] = { 185 #ifdef WITH_OPENSSL 186 {MONITOR_REQ_MODULI, 0, mm_answer_moduli}, 187 #endif 188 {MONITOR_REQ_SIGN, 0, mm_answer_sign}, 189 {MONITOR_REQ_PTY, 0, mm_answer_pty}, 190 {MONITOR_REQ_PTYCLEANUP, 0, mm_answer_pty_cleanup}, 191 {MONITOR_REQ_TERM, 0, mm_answer_term}, 192 {0, 0, NULL} 193 }; 194 195 struct mon_table *mon_dispatch; 196 197 /* Specifies if a certain message is allowed at the moment */ 198 static void 199 monitor_permit(struct mon_table *ent, enum monitor_reqtype type, int permit) 200 { 201 while (ent->f != NULL) { 202 if (ent->type == type) { 203 ent->flags &= ~MON_PERMIT; 204 ent->flags |= permit ? MON_PERMIT : 0; 205 return; 206 } 207 ent++; 208 } 209 } 210 211 static void 212 monitor_permit_authentications(int permit) 213 { 214 struct mon_table *ent = mon_dispatch; 215 216 while (ent->f != NULL) { 217 if (ent->flags & MON_AUTH) { 218 ent->flags &= ~MON_PERMIT; 219 ent->flags |= permit ? MON_PERMIT : 0; 220 } 221 ent++; 222 } 223 } 224 225 void 226 monitor_child_preauth(struct ssh *ssh, struct monitor *pmonitor) 227 { 228 struct mon_table *ent; 229 int authenticated = 0, partial = 0; 230 231 debug3("preauth child monitor started"); 232 233 if (pmonitor->m_recvfd >= 0) 234 close(pmonitor->m_recvfd); 235 if (pmonitor->m_log_sendfd >= 0) 236 close(pmonitor->m_log_sendfd); 237 pmonitor->m_log_sendfd = pmonitor->m_recvfd = -1; 238 239 authctxt = (Authctxt *)ssh->authctxt; 240 memset(authctxt, 0, sizeof(*authctxt)); 241 ssh->authctxt = authctxt; 242 243 mon_dispatch = mon_dispatch_proto20; 244 /* Permit requests for moduli and signatures */ 245 monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); 246 monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); 247 248 /* The first few requests do not require asynchronous access */ 249 while (!authenticated) { 250 partial = 0; 251 auth_method = "unknown"; 252 auth_submethod = NULL; 253 auth2_authctxt_reset_info(authctxt); 254 255 authenticated = (monitor_read(ssh, pmonitor, 256 mon_dispatch, &ent) == 1); 257 258 /* Special handling for multiple required authentications */ 259 if (options.num_auth_methods != 0) { 260 if (authenticated && 261 !auth2_update_methods_lists(authctxt, 262 auth_method, auth_submethod)) { 263 debug3_f("method %s: partial", auth_method); 264 authenticated = 0; 265 partial = 1; 266 } 267 } 268 269 if (authenticated) { 270 if (!(ent->flags & MON_AUTHDECIDE)) 271 fatal_f("unexpected authentication from %d", 272 ent->type); 273 if (authctxt->pw->pw_uid == 0 && 274 !auth_root_allowed(ssh, auth_method)) 275 authenticated = 0; 276 } 277 if (ent->flags & (MON_AUTHDECIDE|MON_ALOG)) { 278 auth_log(ssh, authenticated, partial, 279 auth_method, auth_submethod); 280 if (!partial && !authenticated) 281 authctxt->failures++; 282 if (authenticated || partial) { 283 auth2_update_session_info(authctxt, 284 auth_method, auth_submethod); 285 } 286 } 287 } 288 289 if (!authctxt->valid) 290 fatal_f("authenticated invalid user"); 291 if (strcmp(auth_method, "unknown") == 0) 292 fatal_f("authentication method name unknown"); 293 294 debug_f("user %s authenticated by privileged process", authctxt->user); 295 ssh->authctxt = NULL; 296 ssh_packet_set_log_preamble(ssh, "user %s", authctxt->user); 297 298 mm_get_keystate(ssh, pmonitor); 299 300 /* Drain any buffered messages from the child */ 301 while (pmonitor->m_log_recvfd != -1 && monitor_read_log(pmonitor) == 0) 302 ; 303 304 if (pmonitor->m_recvfd >= 0) 305 close(pmonitor->m_recvfd); 306 if (pmonitor->m_log_sendfd >= 0) 307 close(pmonitor->m_log_sendfd); 308 pmonitor->m_sendfd = pmonitor->m_log_recvfd = -1; 309 } 310 311 static void 312 monitor_set_child_handler(pid_t pid) 313 { 314 monitor_child_pid = pid; 315 } 316 317 static void 318 monitor_child_handler(int sig) 319 { 320 kill(monitor_child_pid, sig); 321 } 322 323 void 324 monitor_child_postauth(struct ssh *ssh, struct monitor *pmonitor) 325 { 326 close(pmonitor->m_recvfd); 327 pmonitor->m_recvfd = -1; 328 329 monitor_set_child_handler(pmonitor->m_pid); 330 ssh_signal(SIGHUP, &monitor_child_handler); 331 ssh_signal(SIGTERM, &monitor_child_handler); 332 ssh_signal(SIGINT, &monitor_child_handler); 333 334 mon_dispatch = mon_dispatch_postauth20; 335 336 /* Permit requests for moduli and signatures */ 337 monitor_permit(mon_dispatch, MONITOR_REQ_MODULI, 1); 338 monitor_permit(mon_dispatch, MONITOR_REQ_SIGN, 1); 339 monitor_permit(mon_dispatch, MONITOR_REQ_TERM, 1); 340 341 if (auth_opts->permit_pty_flag) { 342 monitor_permit(mon_dispatch, MONITOR_REQ_PTY, 1); 343 monitor_permit(mon_dispatch, MONITOR_REQ_PTYCLEANUP, 1); 344 } 345 346 for (;;) 347 monitor_read(ssh, pmonitor, mon_dispatch, NULL); 348 } 349 350 static int 351 monitor_read_log(struct monitor *pmonitor) 352 { 353 struct sshbuf *logmsg; 354 u_int len, level, line; 355 char *msg, *file, *func; 356 u_char *p; 357 int r; 358 359 if ((logmsg = sshbuf_new()) == NULL) 360 fatal_f("sshbuf_new"); 361 362 /* Read length */ 363 if ((r = sshbuf_reserve(logmsg, 4, &p)) != 0) 364 fatal_fr(r, "reserve len"); 365 if (atomicio(read, pmonitor->m_log_recvfd, p, 4) != 4) { 366 if (errno == EPIPE) { 367 sshbuf_free(logmsg); 368 debug_f("child log fd closed"); 369 close(pmonitor->m_log_recvfd); 370 pmonitor->m_log_recvfd = -1; 371 return -1; 372 } 373 fatal_f("log fd read: %s", strerror(errno)); 374 } 375 if ((r = sshbuf_get_u32(logmsg, &len)) != 0) 376 fatal_fr(r, "parse len"); 377 if (len <= 4 || len > 8192) 378 fatal_f("invalid log message length %u", len); 379 380 /* Read severity, message */ 381 sshbuf_reset(logmsg); 382 if ((r = sshbuf_reserve(logmsg, len, &p)) != 0) 383 fatal_fr(r, "reserve msg"); 384 if (atomicio(read, pmonitor->m_log_recvfd, p, len) != len) 385 fatal_f("log fd read: %s", strerror(errno)); 386 if ((r = sshbuf_get_cstring(logmsg, &file, NULL)) != 0 || 387 (r = sshbuf_get_cstring(logmsg, &func, NULL)) != 0 || 388 (r = sshbuf_get_u32(logmsg, &line)) != 0 || 389 (r = sshbuf_get_u32(logmsg, &level)) != 0 || 390 (r = sshbuf_get_cstring(logmsg, &msg, NULL)) != 0) 391 fatal_fr(r, "parse"); 392 393 /* Log it */ 394 if (log_level_name(level) == NULL) 395 fatal_f("invalid log level %u (corrupted message?)", level); 396 sshlog(file, func, line, 0, level, NULL, "%s [preauth]", msg); 397 398 sshbuf_free(logmsg); 399 free(file); 400 free(func); 401 free(msg); 402 403 return 0; 404 } 405 406 static int 407 monitor_read(struct ssh *ssh, struct monitor *pmonitor, struct mon_table *ent, 408 struct mon_table **pent) 409 { 410 struct sshbuf *m; 411 int r, ret; 412 u_char type; 413 struct pollfd pfd[2]; 414 415 for (;;) { 416 memset(&pfd, 0, sizeof(pfd)); 417 pfd[0].fd = pmonitor->m_sendfd; 418 pfd[0].events = POLLIN; 419 pfd[1].fd = pmonitor->m_log_recvfd; 420 pfd[1].events = pfd[1].fd == -1 ? 0 : POLLIN; 421 if (poll(pfd, pfd[1].fd == -1 ? 1 : 2, -1) == -1) { 422 if (errno == EINTR || errno == EAGAIN) 423 continue; 424 fatal_f("poll: %s", strerror(errno)); 425 } 426 if (pfd[1].revents) { 427 /* 428 * Drain all log messages before processing next 429 * monitor request. 430 */ 431 monitor_read_log(pmonitor); 432 continue; 433 } 434 if (pfd[0].revents) 435 break; /* Continues below */ 436 } 437 438 if ((m = sshbuf_new()) == NULL) 439 fatal_f("sshbuf_new"); 440 441 mm_request_receive(pmonitor->m_sendfd, m); 442 if ((r = sshbuf_get_u8(m, &type)) != 0) 443 fatal_fr(r, "parse type"); 444 445 debug3_f("checking request %d", type); 446 447 while (ent->f != NULL) { 448 if (ent->type == type) 449 break; 450 ent++; 451 } 452 453 if (ent->f != NULL) { 454 if (!(ent->flags & MON_PERMIT)) 455 fatal_f("unpermitted request %d", type); 456 ret = (*ent->f)(ssh, pmonitor->m_sendfd, m); 457 sshbuf_free(m); 458 459 /* The child may use this request only once, disable it */ 460 if (ent->flags & MON_ONCE) { 461 debug2_f("%d used once, disabling now", type); 462 ent->flags &= ~MON_PERMIT; 463 } 464 465 if (pent != NULL) 466 *pent = ent; 467 468 return ret; 469 } 470 471 fatal_f("unsupported request: %d", type); 472 473 /* NOTREACHED */ 474 return (-1); 475 } 476 477 /* allowed key state */ 478 static int 479 monitor_allowed_key(const u_char *blob, u_int bloblen) 480 { 481 /* make sure key is allowed */ 482 if (key_blob == NULL || key_bloblen != bloblen || 483 timingsafe_bcmp(key_blob, blob, key_bloblen)) 484 return (0); 485 return (1); 486 } 487 488 static void 489 monitor_reset_key_state(void) 490 { 491 /* reset state */ 492 free(key_blob); 493 free(hostbased_cuser); 494 free(hostbased_chost); 495 sshauthopt_free(key_opts); 496 key_blob = NULL; 497 key_bloblen = 0; 498 key_blobtype = MM_NOKEY; 499 key_opts = NULL; 500 hostbased_cuser = NULL; 501 hostbased_chost = NULL; 502 } 503 504 #ifdef WITH_OPENSSL 505 int 506 mm_answer_moduli(struct ssh *ssh, int sock, struct sshbuf *m) 507 { 508 DH *dh; 509 const BIGNUM *dh_p, *dh_g; 510 int r; 511 u_int min, want, max; 512 513 if ((r = sshbuf_get_u32(m, &min)) != 0 || 514 (r = sshbuf_get_u32(m, &want)) != 0 || 515 (r = sshbuf_get_u32(m, &max)) != 0) 516 fatal_fr(r, "parse"); 517 518 debug3_f("got parameters: %d %d %d", min, want, max); 519 /* We need to check here, too, in case the child got corrupted */ 520 if (max < min || want < min || max < want) 521 fatal_f("bad parameters: %d %d %d", min, want, max); 522 523 sshbuf_reset(m); 524 525 dh = choose_dh(min, want, max); 526 if (dh == NULL) { 527 if ((r = sshbuf_put_u8(m, 0)) != 0) 528 fatal_fr(r, "assemble empty"); 529 return (0); 530 } else { 531 /* Send first bignum */ 532 DH_get0_pqg(dh, &dh_p, NULL, &dh_g); 533 if ((r = sshbuf_put_u8(m, 1)) != 0 || 534 (r = sshbuf_put_bignum2(m, dh_p)) != 0 || 535 (r = sshbuf_put_bignum2(m, dh_g)) != 0) 536 fatal_fr(r, "assemble"); 537 538 DH_free(dh); 539 } 540 mm_request_send(sock, MONITOR_ANS_MODULI, m); 541 return (0); 542 } 543 #endif 544 545 int 546 mm_answer_sign(struct ssh *ssh, int sock, struct sshbuf *m) 547 { 548 extern int auth_sock; /* XXX move to state struct? */ 549 struct sshkey *key; 550 struct sshbuf *sigbuf = NULL; 551 u_char *p = NULL, *signature = NULL; 552 char *alg = NULL; 553 size_t datlen, siglen, alglen; 554 int r, is_proof = 0; 555 u_int keyid, compat; 556 const char proof_req[] = "hostkeys-prove-00@openssh.com"; 557 558 debug3_f("entering"); 559 560 if ((r = sshbuf_get_u32(m, &keyid)) != 0 || 561 (r = sshbuf_get_string(m, &p, &datlen)) != 0 || 562 (r = sshbuf_get_cstring(m, &alg, &alglen)) != 0 || 563 (r = sshbuf_get_u32(m, &compat)) != 0) 564 fatal_fr(r, "parse"); 565 if (keyid > INT_MAX) 566 fatal_f("invalid key ID"); 567 568 /* 569 * Supported KEX types use SHA1 (20 bytes), SHA256 (32 bytes), 570 * SHA384 (48 bytes) and SHA512 (64 bytes). 571 * 572 * Otherwise, verify the signature request is for a hostkey 573 * proof. 574 * 575 * XXX perform similar check for KEX signature requests too? 576 * it's not trivial, since what is signed is the hash, rather 577 * than the full kex structure... 578 */ 579 if (datlen != 20 && datlen != 32 && datlen != 48 && datlen != 64) { 580 /* 581 * Construct expected hostkey proof and compare it to what 582 * the client sent us. 583 */ 584 if (session_id2_len == 0) /* hostkeys is never first */ 585 fatal_f("bad data length: %zu", datlen); 586 if ((key = get_hostkey_public_by_index(keyid, ssh)) == NULL) 587 fatal_f("no hostkey for index %d", keyid); 588 if ((sigbuf = sshbuf_new()) == NULL) 589 fatal_f("sshbuf_new"); 590 if ((r = sshbuf_put_cstring(sigbuf, proof_req)) != 0 || 591 (r = sshbuf_put_string(sigbuf, session_id2, 592 session_id2_len)) != 0 || 593 (r = sshkey_puts(key, sigbuf)) != 0) 594 fatal_fr(r, "assemble private key proof"); 595 if (datlen != sshbuf_len(sigbuf) || 596 memcmp(p, sshbuf_ptr(sigbuf), sshbuf_len(sigbuf)) != 0) 597 fatal_f("bad data length: %zu, hostkey proof len %zu", 598 datlen, sshbuf_len(sigbuf)); 599 sshbuf_free(sigbuf); 600 is_proof = 1; 601 } 602 603 /* save session id, it will be passed on the first call */ 604 if (session_id2_len == 0) { 605 session_id2_len = datlen; 606 session_id2 = xmalloc(session_id2_len); 607 memcpy(session_id2, p, session_id2_len); 608 } 609 610 if ((key = get_hostkey_by_index(keyid)) != NULL) { 611 if ((r = sshkey_sign(key, &signature, &siglen, p, datlen, alg, 612 options.sk_provider, NULL, compat)) != 0) 613 fatal_fr(r, "sign"); 614 } else if ((key = get_hostkey_public_by_index(keyid, ssh)) != NULL && 615 auth_sock > 0) { 616 if ((r = ssh_agent_sign(auth_sock, key, &signature, &siglen, 617 p, datlen, alg, compat)) != 0) 618 fatal_fr(r, "agent sign"); 619 } else 620 fatal_f("no hostkey from index %d", keyid); 621 622 debug3_f("%s signature %p(%zu)", is_proof ? "hostkey proof" : "KEX", 623 signature, siglen); 624 625 sshbuf_reset(m); 626 if ((r = sshbuf_put_string(m, signature, siglen)) != 0) 627 fatal_fr(r, "assemble"); 628 629 free(alg); 630 free(p); 631 free(signature); 632 633 mm_request_send(sock, MONITOR_ANS_SIGN, m); 634 635 /* Turn on permissions for getpwnam */ 636 monitor_permit(mon_dispatch, MONITOR_REQ_PWNAM, 1); 637 638 return (0); 639 } 640 641 #define PUTPW(b, id) \ 642 do { \ 643 if ((r = sshbuf_put_string(b, \ 644 &pwent->id, sizeof(pwent->id))) != 0) \ 645 fatal_fr(r, "assemble %s", #id); \ 646 } while (0) 647 648 /* Retrieves the password entry and also checks if the user is permitted */ 649 int 650 mm_answer_pwnamallow(struct ssh *ssh, int sock, struct sshbuf *m) 651 { 652 char *username; 653 struct passwd *pwent; 654 int r, allowed = 0; 655 u_int i; 656 657 debug3_f("entering"); 658 659 if (authctxt->attempt++ != 0) 660 fatal_f("multiple attempts for getpwnam"); 661 662 if ((r = sshbuf_get_cstring(m, &username, NULL)) != 0) 663 fatal_fr(r, "parse"); 664 665 pwent = getpwnamallow(ssh, username); 666 667 authctxt->user = xstrdup(username); 668 setproctitle("%s [priv]", pwent ? username : "unknown"); 669 free(username); 670 671 sshbuf_reset(m); 672 673 if (pwent == NULL) { 674 if ((r = sshbuf_put_u8(m, 0)) != 0) 675 fatal_fr(r, "assemble fakepw"); 676 authctxt->pw = fakepw(); 677 goto out; 678 } 679 680 allowed = 1; 681 authctxt->pw = pwent; 682 authctxt->valid = 1; 683 684 /* XXX send fake class/dir/shell, etc. */ 685 if ((r = sshbuf_put_u8(m, 1)) != 0) 686 fatal_fr(r, "assemble ok"); 687 PUTPW(m, pw_uid); 688 PUTPW(m, pw_gid); 689 PUTPW(m, pw_change); 690 PUTPW(m, pw_expire); 691 if ((r = sshbuf_put_cstring(m, pwent->pw_name)) != 0 || 692 (r = sshbuf_put_cstring(m, "*")) != 0 || 693 (r = sshbuf_put_cstring(m, pwent->pw_gecos)) != 0 || 694 (r = sshbuf_put_cstring(m, pwent->pw_class)) != 0 || 695 (r = sshbuf_put_cstring(m, pwent->pw_dir)) != 0 || 696 (r = sshbuf_put_cstring(m, pwent->pw_shell)) != 0) 697 fatal_fr(r, "assemble pw"); 698 699 out: 700 ssh_packet_set_log_preamble(ssh, "%suser %s", 701 authctxt->valid ? "authenticating" : "invalid ", authctxt->user); 702 if ((r = sshbuf_put_string(m, &options, sizeof(options))) != 0) 703 fatal_fr(r, "assemble options"); 704 705 #define M_CP_STROPT(x) do { \ 706 if (options.x != NULL && \ 707 (r = sshbuf_put_cstring(m, options.x)) != 0) \ 708 fatal_fr(r, "assemble %s", #x); \ 709 } while (0) 710 #define M_CP_STRARRAYOPT(x, nx) do { \ 711 for (i = 0; i < options.nx; i++) { \ 712 if ((r = sshbuf_put_cstring(m, options.x[i])) != 0) \ 713 fatal_fr(r, "assemble %s", #x); \ 714 } \ 715 } while (0) 716 /* See comment in servconf.h */ 717 COPY_MATCH_STRING_OPTS(); 718 #undef M_CP_STROPT 719 #undef M_CP_STRARRAYOPT 720 721 /* Create valid auth method lists */ 722 if (auth2_setup_methods_lists(authctxt) != 0) { 723 /* 724 * The monitor will continue long enough to let the child 725 * run to it's packet_disconnect(), but it must not allow any 726 * authentication to succeed. 727 */ 728 debug_f("no valid authentication method lists"); 729 } 730 731 debug3_f("sending MONITOR_ANS_PWNAM: %d", allowed); 732 mm_request_send(sock, MONITOR_ANS_PWNAM, m); 733 734 /* Allow service/style information on the auth context */ 735 monitor_permit(mon_dispatch, MONITOR_REQ_AUTHSERV, 1); 736 monitor_permit(mon_dispatch, MONITOR_REQ_AUTH2_READ_BANNER, 1); 737 738 return (0); 739 } 740 741 int mm_answer_auth2_read_banner(struct ssh *ssh, int sock, struct sshbuf *m) 742 { 743 char *banner; 744 int r; 745 746 sshbuf_reset(m); 747 banner = auth2_read_banner(); 748 if ((r = sshbuf_put_cstring(m, banner != NULL ? banner : "")) != 0) 749 fatal_fr(r, "assemble"); 750 mm_request_send(sock, MONITOR_ANS_AUTH2_READ_BANNER, m); 751 free(banner); 752 753 return (0); 754 } 755 756 int 757 mm_answer_authserv(struct ssh *ssh, int sock, struct sshbuf *m) 758 { 759 int r; 760 761 monitor_permit_authentications(1); 762 763 if ((r = sshbuf_get_cstring(m, &authctxt->service, NULL)) != 0 || 764 (r = sshbuf_get_cstring(m, &authctxt->style, NULL)) != 0) 765 fatal_fr(r, "parse"); 766 debug3_f("service=%s, style=%s", authctxt->service, authctxt->style); 767 768 if (strlen(authctxt->style) == 0) { 769 free(authctxt->style); 770 authctxt->style = NULL; 771 } 772 773 return (0); 774 } 775 776 int 777 mm_answer_authpassword(struct ssh *ssh, int sock, struct sshbuf *m) 778 { 779 static int call_count; 780 char *passwd; 781 int r, authenticated; 782 size_t plen; 783 784 if (!options.password_authentication) 785 fatal_f("password authentication not enabled"); 786 if ((r = sshbuf_get_cstring(m, &passwd, &plen)) != 0) 787 fatal_fr(r, "parse"); 788 /* Only authenticate if the context is valid */ 789 authenticated = options.password_authentication && 790 auth_password(ssh, passwd); 791 freezero(passwd, plen); 792 793 sshbuf_reset(m); 794 if ((r = sshbuf_put_u32(m, authenticated)) != 0) 795 fatal_fr(r, "assemble"); 796 797 debug3_f("sending result %d", authenticated); 798 mm_request_send(sock, MONITOR_ANS_AUTHPASSWORD, m); 799 800 call_count++; 801 if (plen == 0 && call_count == 1) 802 auth_method = "none"; 803 else 804 auth_method = "password"; 805 806 /* Causes monitor loop to terminate if authenticated */ 807 return (authenticated); 808 } 809 810 int 811 mm_answer_bsdauthquery(struct ssh *ssh, int sock, struct sshbuf *m) 812 { 813 char *name, *infotxt; 814 u_int numprompts, *echo_on, success; 815 char **prompts; 816 int r; 817 818 if (!options.kbd_interactive_authentication) 819 fatal_f("kbd-int authentication not enabled"); 820 success = bsdauth_query(authctxt, &name, &infotxt, &numprompts, 821 &prompts, &echo_on) < 0 ? 0 : 1; 822 823 sshbuf_reset(m); 824 if ((r = sshbuf_put_u32(m, success)) != 0) 825 fatal_fr(r, "assemble"); 826 if (success) { 827 if ((r = sshbuf_put_cstring(m, prompts[0])) != 0) 828 fatal_fr(r, "assemble prompt"); 829 } 830 831 debug3_f("sending challenge success: %u", success); 832 mm_request_send(sock, MONITOR_ANS_BSDAUTHQUERY, m); 833 834 if (success) { 835 free(name); 836 free(infotxt); 837 free(prompts); 838 free(echo_on); 839 } 840 841 return (0); 842 } 843 844 int 845 mm_answer_bsdauthrespond(struct ssh *ssh, int sock, struct sshbuf *m) 846 { 847 char *response; 848 int r, authok; 849 850 if (!options.kbd_interactive_authentication) 851 fatal_f("kbd-int authentication not enabled"); 852 if (authctxt->as == NULL) 853 fatal_f("no bsd auth session"); 854 855 if ((r = sshbuf_get_cstring(m, &response, NULL)) != 0) 856 fatal_fr(r, "parse"); 857 authok = options.challenge_response_authentication && 858 auth_userresponse(authctxt->as, response, 0); 859 authctxt->as = NULL; 860 debug3_f("<%s> = <%d>", response, authok); 861 free(response); 862 863 sshbuf_reset(m); 864 if ((r = sshbuf_put_u32(m, authok)) != 0) 865 fatal_fr(r, "assemble"); 866 867 debug3_f("sending authenticated: %d", authok); 868 mm_request_send(sock, MONITOR_ANS_BSDAUTHRESPOND, m); 869 870 auth_method = "keyboard-interactive"; 871 auth_submethod = "bsdauth"; 872 873 return (authok != 0); 874 } 875 876 /* 877 * Check that the key type appears in the supplied pattern list, ignoring 878 * mismatches in the signature algorithm. (Signature algorithm checks are 879 * performed in the unprivileged authentication code). 880 * Returns 1 on success, 0 otherwise. 881 */ 882 static int 883 key_base_type_match(const char *method, const struct sshkey *key, 884 const char *list) 885 { 886 char *s, *l, *ol = xstrdup(list); 887 int found = 0; 888 889 l = ol; 890 for ((s = strsep(&l, ",")); s && *s != '\0'; (s = strsep(&l, ","))) { 891 if (sshkey_type_from_name(s) == key->type) { 892 found = 1; 893 break; 894 } 895 } 896 if (!found) { 897 error("%s key type %s is not in permitted list %s", method, 898 sshkey_ssh_name(key), list); 899 } 900 901 free(ol); 902 return found; 903 } 904 905 int 906 mm_answer_keyallowed(struct ssh *ssh, int sock, struct sshbuf *m) 907 { 908 struct sshkey *key = NULL; 909 char *cuser, *chost; 910 u_int pubkey_auth_attempt; 911 enum mm_keytype type = 0; 912 int r, allowed = 0; 913 struct sshauthopt *opts = NULL; 914 915 debug3_f("entering"); 916 if ((r = sshbuf_get_u32(m, &type)) != 0 || 917 (r = sshbuf_get_cstring(m, &cuser, NULL)) != 0 || 918 (r = sshbuf_get_cstring(m, &chost, NULL)) != 0 || 919 (r = sshkey_froms(m, &key)) != 0 || 920 (r = sshbuf_get_u32(m, &pubkey_auth_attempt)) != 0) 921 fatal_fr(r, "parse"); 922 923 debug3_f("key_from_blob: %p", key); 924 925 if (key != NULL && authctxt->valid) { 926 /* These should not make it past the privsep child */ 927 if (sshkey_type_plain(key->type) == KEY_RSA && 928 (ssh->compat & SSH_BUG_RSASIGMD5) != 0) 929 fatal_f("passed a SSH_BUG_RSASIGMD5 key"); 930 931 switch (type) { 932 case MM_USERKEY: 933 auth_method = "publickey"; 934 if (!options.pubkey_authentication) 935 break; 936 if (auth2_key_already_used(authctxt, key)) 937 break; 938 if (!key_base_type_match(auth_method, key, 939 options.pubkey_accepted_algos)) 940 break; 941 allowed = user_key_allowed(ssh, authctxt->pw, key, 942 pubkey_auth_attempt, &opts); 943 break; 944 case MM_HOSTKEY: 945 auth_method = "hostbased"; 946 if (!options.hostbased_authentication) 947 break; 948 if (auth2_key_already_used(authctxt, key)) 949 break; 950 if (!key_base_type_match(auth_method, key, 951 options.hostbased_accepted_algos)) 952 break; 953 allowed = hostbased_key_allowed(ssh, authctxt->pw, 954 cuser, chost, key); 955 auth2_record_info(authctxt, 956 "client user \"%.100s\", client host \"%.100s\"", 957 cuser, chost); 958 break; 959 default: 960 fatal_f("unknown key type %d", type); 961 break; 962 } 963 } 964 965 debug3_f("%s authentication%s: %s key is %s", auth_method, 966 pubkey_auth_attempt ? "" : " test", 967 (key == NULL || !authctxt->valid) ? "invalid" : sshkey_type(key), 968 allowed ? "allowed" : "not allowed"); 969 970 auth2_record_key(authctxt, 0, key); 971 972 /* clear temporarily storage (used by verify) */ 973 monitor_reset_key_state(); 974 975 if (allowed) { 976 /* Save temporarily for comparison in verify */ 977 if ((r = sshkey_to_blob(key, &key_blob, &key_bloblen)) != 0) 978 fatal_fr(r, "sshkey_to_blob"); 979 key_blobtype = type; 980 key_opts = opts; 981 hostbased_cuser = cuser; 982 hostbased_chost = chost; 983 } else { 984 /* Log failed attempt */ 985 auth_log(ssh, 0, 0, auth_method, NULL); 986 free(cuser); 987 free(chost); 988 } 989 sshkey_free(key); 990 991 sshbuf_reset(m); 992 if ((r = sshbuf_put_u32(m, allowed)) != 0) 993 fatal_fr(r, "assemble"); 994 if (opts != NULL && (r = sshauthopt_serialise(opts, m, 1)) != 0) 995 fatal_fr(r, "sshauthopt_serialise"); 996 mm_request_send(sock, MONITOR_ANS_KEYALLOWED, m); 997 998 if (!allowed) 999 sshauthopt_free(opts); 1000 1001 return (0); 1002 } 1003 1004 static int 1005 monitor_valid_userblob(struct ssh *ssh, const u_char *data, u_int datalen) 1006 { 1007 struct sshbuf *b; 1008 const u_char *p; 1009 char *userstyle, *cp; 1010 size_t len; 1011 u_char type; 1012 int r, fail = 0; 1013 1014 if ((b = sshbuf_from(data, datalen)) == NULL) 1015 fatal_f("sshbuf_from"); 1016 1017 if (ssh->compat & SSH_OLD_SESSIONID) { 1018 p = sshbuf_ptr(b); 1019 len = sshbuf_len(b); 1020 if ((session_id2 == NULL) || 1021 (len < session_id2_len) || 1022 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) 1023 fail++; 1024 if ((r = sshbuf_consume(b, session_id2_len)) != 0) 1025 fatal_fr(r, "consume"); 1026 } else { 1027 if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0) 1028 fatal_fr(r, "parse sessionid"); 1029 if ((session_id2 == NULL) || 1030 (len != session_id2_len) || 1031 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) 1032 fail++; 1033 } 1034 if ((r = sshbuf_get_u8(b, &type)) != 0) 1035 fatal_fr(r, "parse type"); 1036 if (type != SSH2_MSG_USERAUTH_REQUEST) 1037 fail++; 1038 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1039 fatal_fr(r, "parse userstyle"); 1040 xasprintf(&userstyle, "%s%s%s", authctxt->user, 1041 authctxt->style ? ":" : "", 1042 authctxt->style ? authctxt->style : ""); 1043 if (strcmp(userstyle, cp) != 0) { 1044 logit("wrong user name passed to monitor: " 1045 "expected %s != %.100s", userstyle, cp); 1046 fail++; 1047 } 1048 free(userstyle); 1049 free(cp); 1050 if ((r = sshbuf_skip_string(b)) != 0 || /* service */ 1051 (r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1052 fatal_fr(r, "parse method"); 1053 if (strcmp("publickey", cp) != 0) 1054 fail++; 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 fatal_fr(r, "parse pk"); 1063 if (sshbuf_len(b) != 0) 1064 fail++; 1065 sshbuf_free(b); 1066 return (fail == 0); 1067 } 1068 1069 static int 1070 monitor_valid_hostbasedblob(const u_char *data, u_int datalen, 1071 const char *cuser, const char *chost) 1072 { 1073 struct sshbuf *b; 1074 const u_char *p; 1075 char *cp, *userstyle; 1076 size_t len; 1077 int r, fail = 0; 1078 u_char type; 1079 1080 if ((b = sshbuf_from(data, datalen)) == NULL) 1081 fatal_f("sshbuf_new"); 1082 if ((r = sshbuf_get_string_direct(b, &p, &len)) != 0) 1083 fatal_fr(r, "parse sessionid"); 1084 1085 if ((session_id2 == NULL) || 1086 (len != session_id2_len) || 1087 (timingsafe_bcmp(p, session_id2, session_id2_len) != 0)) 1088 fail++; 1089 1090 if ((r = sshbuf_get_u8(b, &type)) != 0) 1091 fatal_fr(r, "parse type"); 1092 if (type != SSH2_MSG_USERAUTH_REQUEST) 1093 fail++; 1094 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1095 fatal_fr(r, "parse userstyle"); 1096 xasprintf(&userstyle, "%s%s%s", authctxt->user, 1097 authctxt->style ? ":" : "", 1098 authctxt->style ? authctxt->style : ""); 1099 if (strcmp(userstyle, cp) != 0) { 1100 logit("wrong user name passed to monitor: " 1101 "expected %s != %.100s", userstyle, cp); 1102 fail++; 1103 } 1104 free(userstyle); 1105 free(cp); 1106 if ((r = sshbuf_skip_string(b)) != 0 || /* service */ 1107 (r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1108 fatal_fr(r, "parse method"); 1109 if (strcmp(cp, "hostbased") != 0) 1110 fail++; 1111 free(cp); 1112 if ((r = sshbuf_skip_string(b)) != 0 || /* pkalg */ 1113 (r = sshbuf_skip_string(b)) != 0) /* pkblob */ 1114 fatal_fr(r, "parse pk"); 1115 1116 /* verify client host, strip trailing dot if necessary */ 1117 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1118 fatal_fr(r, "parse host"); 1119 if (((len = strlen(cp)) > 0) && cp[len - 1] == '.') 1120 cp[len - 1] = '\0'; 1121 if (strcmp(cp, chost) != 0) 1122 fail++; 1123 free(cp); 1124 1125 /* verify client user */ 1126 if ((r = sshbuf_get_cstring(b, &cp, NULL)) != 0) 1127 fatal_fr(r, "parse ruser"); 1128 if (strcmp(cp, cuser) != 0) 1129 fail++; 1130 free(cp); 1131 1132 if (sshbuf_len(b) != 0) 1133 fail++; 1134 sshbuf_free(b); 1135 return (fail == 0); 1136 } 1137 1138 int 1139 mm_answer_keyverify(struct ssh *ssh, int sock, struct sshbuf *m) 1140 { 1141 struct sshkey *key; 1142 const u_char *signature, *data, *blob; 1143 char *sigalg = NULL, *fp = NULL; 1144 size_t signaturelen, datalen, bloblen; 1145 int r, ret, req_presence = 0, req_verify = 0, valid_data = 0; 1146 int encoded_ret; 1147 struct sshkey_sig_details *sig_details = NULL; 1148 1149 if ((r = sshbuf_get_string_direct(m, &blob, &bloblen)) != 0 || 1150 (r = sshbuf_get_string_direct(m, &signature, &signaturelen)) != 0 || 1151 (r = sshbuf_get_string_direct(m, &data, &datalen)) != 0 || 1152 (r = sshbuf_get_cstring(m, &sigalg, NULL)) != 0) 1153 fatal_fr(r, "parse"); 1154 1155 if (hostbased_cuser == NULL || hostbased_chost == NULL || 1156 !monitor_allowed_key(blob, bloblen)) 1157 fatal_f("bad key, not previously allowed"); 1158 1159 /* Empty signature algorithm means NULL. */ 1160 if (*sigalg == '\0') { 1161 free(sigalg); 1162 sigalg = NULL; 1163 } 1164 1165 /* XXX use sshkey_froms here; need to change key_blob, etc. */ 1166 if ((r = sshkey_from_blob(blob, bloblen, &key)) != 0) 1167 fatal_fr(r, "parse key"); 1168 1169 switch (key_blobtype) { 1170 case MM_USERKEY: 1171 valid_data = monitor_valid_userblob(ssh, data, datalen); 1172 auth_method = "publickey"; 1173 break; 1174 case MM_HOSTKEY: 1175 valid_data = monitor_valid_hostbasedblob(data, datalen, 1176 hostbased_cuser, hostbased_chost); 1177 auth_method = "hostbased"; 1178 break; 1179 default: 1180 valid_data = 0; 1181 break; 1182 } 1183 if (!valid_data) 1184 fatal_f("bad %s signature data blob", 1185 key_blobtype == MM_USERKEY ? "userkey" : 1186 (key_blobtype == MM_HOSTKEY ? "hostkey" : "unknown")); 1187 1188 if ((fp = sshkey_fingerprint(key, options.fingerprint_hash, 1189 SSH_FP_DEFAULT)) == NULL) 1190 fatal_f("sshkey_fingerprint failed"); 1191 1192 ret = sshkey_verify(key, signature, signaturelen, data, datalen, 1193 sigalg, ssh->compat, &sig_details); 1194 debug3_f("%s %p signature %s%s%s", auth_method, key, 1195 (ret == 0) ? "verified" : "unverified", 1196 (ret != 0) ? ": " : "", (ret != 0) ? ssh_err(ret) : ""); 1197 1198 if (ret == 0 && key_blobtype == MM_USERKEY && sig_details != NULL) { 1199 req_presence = (options.pubkey_auth_options & 1200 PUBKEYAUTH_TOUCH_REQUIRED) || 1201 !key_opts->no_require_user_presence; 1202 if (req_presence && 1203 (sig_details->sk_flags & SSH_SK_USER_PRESENCE_REQD) == 0) { 1204 error("public key %s %s signature for %s%s from %.128s " 1205 "port %d rejected: user presence " 1206 "(authenticator touch) requirement not met ", 1207 sshkey_type(key), fp, 1208 authctxt->valid ? "" : "invalid user ", 1209 authctxt->user, ssh_remote_ipaddr(ssh), 1210 ssh_remote_port(ssh)); 1211 ret = SSH_ERR_SIGNATURE_INVALID; 1212 } 1213 req_verify = (options.pubkey_auth_options & 1214 PUBKEYAUTH_VERIFY_REQUIRED) || key_opts->require_verify; 1215 if (req_verify && 1216 (sig_details->sk_flags & SSH_SK_USER_VERIFICATION_REQD) == 0) { 1217 error("public key %s %s signature for %s%s from %.128s " 1218 "port %d rejected: user verification requirement " 1219 "not met ", 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 } 1226 auth2_record_key(authctxt, ret == 0, key); 1227 1228 if (key_blobtype == MM_USERKEY) 1229 auth_activate_options(ssh, key_opts); 1230 monitor_reset_key_state(); 1231 1232 sshbuf_reset(m); 1233 1234 /* encode ret != 0 as positive integer, since we're sending u32 */ 1235 encoded_ret = (ret != 0); 1236 if ((r = sshbuf_put_u32(m, encoded_ret)) != 0 || 1237 (r = sshbuf_put_u8(m, sig_details != NULL)) != 0) 1238 fatal_fr(r, "assemble"); 1239 if (sig_details != NULL) { 1240 if ((r = sshbuf_put_u32(m, sig_details->sk_counter)) != 0 || 1241 (r = sshbuf_put_u8(m, sig_details->sk_flags)) != 0) 1242 fatal_fr(r, "assemble sk"); 1243 } 1244 sshkey_sig_details_free(sig_details); 1245 mm_request_send(sock, MONITOR_ANS_KEYVERIFY, m); 1246 1247 free(sigalg); 1248 free(fp); 1249 sshkey_free(key); 1250 1251 return ret == 0; 1252 } 1253 1254 static void 1255 mm_record_login(struct ssh *ssh, Session *s, struct passwd *pw) 1256 { 1257 socklen_t fromlen; 1258 struct sockaddr_storage from; 1259 1260 /* 1261 * Get IP address of client. If the connection is not a socket, let 1262 * the address be 0.0.0.0. 1263 */ 1264 memset(&from, 0, sizeof(from)); 1265 fromlen = sizeof(from); 1266 if (ssh_packet_connection_is_on_socket(ssh)) { 1267 if (getpeername(ssh_packet_get_connection_in(ssh), 1268 (struct sockaddr *)&from, &fromlen) == -1) { 1269 debug("getpeername: %.100s", strerror(errno)); 1270 cleanup_exit(255); 1271 } 1272 } 1273 /* Record that there was a login on that tty from the remote host. */ 1274 record_login(s->pid, s->tty, pw->pw_name, pw->pw_uid, 1275 session_get_remote_name_or_ip(ssh, utmp_len, options.use_dns), 1276 (struct sockaddr *)&from, fromlen); 1277 } 1278 1279 static void 1280 mm_session_close(Session *s) 1281 { 1282 debug3_f("session %d pid %ld", s->self, (long)s->pid); 1283 if (s->ttyfd != -1) { 1284 debug3_f("tty %s ptyfd %d", s->tty, s->ptyfd); 1285 session_pty_cleanup2(s); 1286 } 1287 session_unused(s->self); 1288 } 1289 1290 int 1291 mm_answer_pty(struct ssh *ssh, int sock, struct sshbuf *m) 1292 { 1293 extern struct monitor *pmonitor; 1294 Session *s; 1295 int r, res, fd0; 1296 1297 debug3_f("entering"); 1298 1299 sshbuf_reset(m); 1300 s = session_new(); 1301 if (s == NULL) 1302 goto error; 1303 s->authctxt = authctxt; 1304 s->pw = authctxt->pw; 1305 s->pid = pmonitor->m_pid; 1306 res = pty_allocate(&s->ptyfd, &s->ttyfd, s->tty, sizeof(s->tty)); 1307 if (res == 0) 1308 goto error; 1309 pty_setowner(authctxt->pw, s->tty); 1310 1311 if ((r = sshbuf_put_u32(m, 1)) != 0 || 1312 (r = sshbuf_put_cstring(m, s->tty)) != 0) 1313 fatal_fr(r, "assemble"); 1314 1315 /* We need to trick ttyslot */ 1316 if (dup2(s->ttyfd, 0) == -1) 1317 fatal_f("dup2"); 1318 1319 mm_record_login(ssh, s, authctxt->pw); 1320 1321 /* Now we can close the file descriptor again */ 1322 close(0); 1323 1324 /* send messages generated by record_login */ 1325 if ((r = sshbuf_put_stringb(m, loginmsg)) != 0) 1326 fatal_fr(r, "assemble loginmsg"); 1327 sshbuf_reset(loginmsg); 1328 1329 mm_request_send(sock, MONITOR_ANS_PTY, m); 1330 1331 if (mm_send_fd(sock, s->ptyfd) == -1 || 1332 mm_send_fd(sock, s->ttyfd) == -1) 1333 fatal_f("send fds failed"); 1334 1335 /* make sure nothing uses fd 0 */ 1336 if ((fd0 = open(_PATH_DEVNULL, O_RDONLY)) == -1) 1337 fatal_f("open(/dev/null): %s", strerror(errno)); 1338 if (fd0 != 0) 1339 error_f("fd0 %d != 0", fd0); 1340 1341 /* slave side of pty is not needed */ 1342 close(s->ttyfd); 1343 s->ttyfd = s->ptyfd; 1344 /* no need to dup() because nobody closes ptyfd */ 1345 s->ptymaster = s->ptyfd; 1346 1347 debug3_f("tty %s ptyfd %d", s->tty, s->ttyfd); 1348 1349 return (0); 1350 1351 error: 1352 if (s != NULL) 1353 mm_session_close(s); 1354 if ((r = sshbuf_put_u32(m, 0)) != 0) 1355 fatal_fr(r, "assemble 0"); 1356 mm_request_send(sock, MONITOR_ANS_PTY, m); 1357 return (0); 1358 } 1359 1360 int 1361 mm_answer_pty_cleanup(struct ssh *ssh, int sock, struct sshbuf *m) 1362 { 1363 Session *s; 1364 char *tty; 1365 int r; 1366 1367 debug3_f("entering"); 1368 1369 if ((r = sshbuf_get_cstring(m, &tty, NULL)) != 0) 1370 fatal_fr(r, "parse tty"); 1371 if ((s = session_by_tty(tty)) != NULL) 1372 mm_session_close(s); 1373 sshbuf_reset(m); 1374 free(tty); 1375 return (0); 1376 } 1377 1378 int 1379 mm_answer_term(struct ssh *ssh, int sock, struct sshbuf *req) 1380 { 1381 extern struct monitor *pmonitor; 1382 int res, status; 1383 1384 debug3_f("tearing down sessions"); 1385 1386 /* The child is terminating */ 1387 session_destroy_all(ssh, &mm_session_close); 1388 1389 while (waitpid(pmonitor->m_pid, &status, 0) == -1) 1390 if (errno != EINTR) 1391 exit(1); 1392 1393 res = WIFEXITED(status) ? WEXITSTATUS(status) : 1; 1394 1395 /* Terminate process */ 1396 exit(res); 1397 } 1398 1399 void 1400 monitor_clear_keystate(struct ssh *ssh, struct monitor *pmonitor) 1401 { 1402 ssh_clear_newkeys(ssh, MODE_IN); 1403 ssh_clear_newkeys(ssh, MODE_OUT); 1404 sshbuf_free(child_state); 1405 child_state = NULL; 1406 } 1407 1408 void 1409 monitor_apply_keystate(struct ssh *ssh, struct monitor *pmonitor) 1410 { 1411 struct kex *kex; 1412 int r; 1413 1414 debug3_f("packet_set_state"); 1415 if ((r = ssh_packet_set_state(ssh, child_state)) != 0) 1416 fatal_fr(r, "packet_set_state"); 1417 sshbuf_free(child_state); 1418 child_state = NULL; 1419 if ((kex = ssh->kex) == NULL) 1420 fatal_f("internal error: ssh->kex == NULL"); 1421 if (session_id2_len != sshbuf_len(ssh->kex->session_id)) { 1422 fatal_f("incorrect session id length %zu (expected %u)", 1423 sshbuf_len(ssh->kex->session_id), session_id2_len); 1424 } 1425 if (memcmp(sshbuf_ptr(ssh->kex->session_id), session_id2, 1426 session_id2_len) != 0) 1427 fatal_f("session ID mismatch"); 1428 /* XXX set callbacks */ 1429 #ifdef WITH_OPENSSL 1430 kex->kex[KEX_DH_GRP1_SHA1] = kex_gen_server; 1431 kex->kex[KEX_DH_GRP14_SHA1] = kex_gen_server; 1432 kex->kex[KEX_DH_GRP14_SHA256] = kex_gen_server; 1433 kex->kex[KEX_DH_GRP16_SHA512] = kex_gen_server; 1434 kex->kex[KEX_DH_GRP18_SHA512] = kex_gen_server; 1435 kex->kex[KEX_DH_GEX_SHA1] = kexgex_server; 1436 kex->kex[KEX_DH_GEX_SHA256] = kexgex_server; 1437 kex->kex[KEX_ECDH_SHA2] = kex_gen_server; 1438 #endif 1439 kex->kex[KEX_C25519_SHA256] = kex_gen_server; 1440 kex->kex[KEX_KEM_SNTRUP761X25519_SHA512] = kex_gen_server; 1441 kex->load_host_public_key=&get_hostkey_public_by_type; 1442 kex->load_host_private_key=&get_hostkey_private_by_type; 1443 kex->host_key_index=&get_hostkey_index; 1444 kex->sign = sshd_hostkey_sign; 1445 } 1446 1447 /* This function requires careful sanity checking */ 1448 1449 void 1450 mm_get_keystate(struct ssh *ssh, struct monitor *pmonitor) 1451 { 1452 debug3_f("Waiting for new keys"); 1453 1454 if ((child_state = sshbuf_new()) == NULL) 1455 fatal_f("sshbuf_new failed"); 1456 mm_request_receive_expect(pmonitor->m_sendfd, MONITOR_REQ_KEYEXPORT, 1457 child_state); 1458 debug3_f("GOT new keys"); 1459 } 1460 1461 1462 /* XXX */ 1463 1464 #define FD_CLOSEONEXEC(x) do { \ 1465 if (fcntl(x, F_SETFD, FD_CLOEXEC) == -1) \ 1466 fatal("fcntl(%d, F_SETFD)", x); \ 1467 } while (0) 1468 1469 static void 1470 monitor_openfds(struct monitor *mon, int do_logfds) 1471 { 1472 int pair[2]; 1473 #ifdef SO_ZEROIZE 1474 int on = 1; 1475 #endif 1476 1477 if (socketpair(AF_UNIX, SOCK_STREAM, 0, pair) == -1) 1478 fatal_f("socketpair: %s", strerror(errno)); 1479 #ifdef SO_ZEROIZE 1480 if (setsockopt(pair[0], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1) 1481 error("setsockopt SO_ZEROIZE(0): %.100s", strerror(errno)); 1482 if (setsockopt(pair[1], SOL_SOCKET, SO_ZEROIZE, &on, sizeof(on)) == -1) 1483 error("setsockopt SO_ZEROIZE(1): %.100s", strerror(errno)); 1484 #endif 1485 FD_CLOSEONEXEC(pair[0]); 1486 FD_CLOSEONEXEC(pair[1]); 1487 mon->m_recvfd = pair[0]; 1488 mon->m_sendfd = pair[1]; 1489 1490 if (do_logfds) { 1491 if (pipe(pair) == -1) 1492 fatal_f("pipe: %s", strerror(errno)); 1493 FD_CLOSEONEXEC(pair[0]); 1494 FD_CLOSEONEXEC(pair[1]); 1495 mon->m_log_recvfd = pair[0]; 1496 mon->m_log_sendfd = pair[1]; 1497 } else 1498 mon->m_log_recvfd = mon->m_log_sendfd = -1; 1499 } 1500 1501 #define MM_MEMSIZE 65536 1502 1503 struct monitor * 1504 monitor_init(void) 1505 { 1506 struct monitor *mon; 1507 1508 mon = xcalloc(1, sizeof(*mon)); 1509 monitor_openfds(mon, 1); 1510 1511 return mon; 1512 } 1513 1514 void 1515 monitor_reinit(struct monitor *mon) 1516 { 1517 monitor_openfds(mon, 0); 1518 } 1519 1520 #ifdef GSSAPI 1521 int 1522 mm_answer_gss_setup_ctx(struct ssh *ssh, int sock, struct sshbuf *m) 1523 { 1524 gss_OID_desc goid; 1525 OM_uint32 major; 1526 size_t len; 1527 u_char *p; 1528 int r; 1529 1530 if (!options.gss_authentication) 1531 fatal_f("GSSAPI authentication not enabled"); 1532 1533 if ((r = sshbuf_get_string(m, &p, &len)) != 0) 1534 fatal_fr(r, "parse"); 1535 goid.elements = p; 1536 goid.length = len; 1537 1538 major = ssh_gssapi_server_ctx(&gsscontext, &goid); 1539 1540 free(goid.elements); 1541 1542 sshbuf_reset(m); 1543 if ((r = sshbuf_put_u32(m, major)) != 0) 1544 fatal_fr(r, "assemble"); 1545 1546 mm_request_send(sock, MONITOR_ANS_GSSSETUP, m); 1547 1548 /* Now we have a context, enable the step */ 1549 monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 1); 1550 1551 return (0); 1552 } 1553 1554 int 1555 mm_answer_gss_accept_ctx(struct ssh *ssh, int sock, struct sshbuf *m) 1556 { 1557 gss_buffer_desc in; 1558 gss_buffer_desc out = GSS_C_EMPTY_BUFFER; 1559 OM_uint32 major, minor; 1560 OM_uint32 flags = 0; /* GSI needs this */ 1561 int r; 1562 1563 if (!options.gss_authentication) 1564 fatal_f("GSSAPI authentication not enabled"); 1565 1566 if ((r = ssh_gssapi_get_buffer_desc(m, &in)) != 0) 1567 fatal_fr(r, "ssh_gssapi_get_buffer_desc"); 1568 major = ssh_gssapi_accept_ctx(gsscontext, &in, &out, &flags); 1569 free(in.value); 1570 1571 sshbuf_reset(m); 1572 if ((r = sshbuf_put_u32(m, major)) != 0 || 1573 (r = sshbuf_put_string(m, out.value, out.length)) != 0 || 1574 (r = sshbuf_put_u32(m, flags)) != 0) 1575 fatal_fr(r, "assemble"); 1576 mm_request_send(sock, MONITOR_ANS_GSSSTEP, m); 1577 1578 gss_release_buffer(&minor, &out); 1579 1580 if (major == GSS_S_COMPLETE) { 1581 monitor_permit(mon_dispatch, MONITOR_REQ_GSSSTEP, 0); 1582 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1); 1583 monitor_permit(mon_dispatch, MONITOR_REQ_GSSCHECKMIC, 1); 1584 } 1585 return (0); 1586 } 1587 1588 int 1589 mm_answer_gss_checkmic(struct ssh *ssh, int sock, struct sshbuf *m) 1590 { 1591 gss_buffer_desc gssbuf, mic; 1592 OM_uint32 ret; 1593 int r; 1594 1595 if (!options.gss_authentication) 1596 fatal_f("GSSAPI authentication not enabled"); 1597 1598 if ((r = ssh_gssapi_get_buffer_desc(m, &gssbuf)) != 0 || 1599 (r = ssh_gssapi_get_buffer_desc(m, &mic)) != 0) 1600 fatal_fr(r, "ssh_gssapi_get_buffer_desc"); 1601 1602 ret = ssh_gssapi_checkmic(gsscontext, &gssbuf, &mic); 1603 1604 free(gssbuf.value); 1605 free(mic.value); 1606 1607 sshbuf_reset(m); 1608 if ((r = sshbuf_put_u32(m, ret)) != 0) 1609 fatal_fr(r, "assemble"); 1610 1611 mm_request_send(sock, MONITOR_ANS_GSSCHECKMIC, m); 1612 1613 if (!GSS_ERROR(ret)) 1614 monitor_permit(mon_dispatch, MONITOR_REQ_GSSUSEROK, 1); 1615 1616 return (0); 1617 } 1618 1619 int 1620 mm_answer_gss_userok(struct ssh *ssh, int sock, struct sshbuf *m) 1621 { 1622 int r, authenticated; 1623 const char *displayname; 1624 1625 if (!options.gss_authentication) 1626 fatal_f("GSSAPI authentication not enabled"); 1627 1628 authenticated = authctxt->valid && ssh_gssapi_userok(authctxt->user); 1629 1630 sshbuf_reset(m); 1631 if ((r = sshbuf_put_u32(m, authenticated)) != 0) 1632 fatal_fr(r, "assemble"); 1633 1634 debug3_f("sending result %d", authenticated); 1635 mm_request_send(sock, MONITOR_ANS_GSSUSEROK, m); 1636 1637 auth_method = "gssapi-with-mic"; 1638 1639 if ((displayname = ssh_gssapi_displayname()) != NULL) 1640 auth2_record_info(authctxt, "%s", displayname); 1641 1642 /* Monitor loop will terminate if authenticated */ 1643 return (authenticated); 1644 } 1645 #endif /* GSSAPI */ 1646 1647