1 /*- 2 * Copyright (c) 2002 Networks Associates Technology, Inc. 3 * All rights reserved. 4 * 5 * This software was developed for the FreeBSD Project by ThinkSec AS and 6 * NAI Labs, the Security Research Division of Network Associates, Inc. 7 * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the 8 * DARPA CHATS research program. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29 * SUCH DAMAGE. 30 */ 31 /* 32 * Copyright (c) 2003,2004 Damien Miller <djm@mindrot.org> 33 * Copyright (c) 2003,2004 Darren Tucker <dtucker@zip.com.au> 34 * 35 * Permission to use, copy, modify, and distribute this software for any 36 * purpose with or without fee is hereby granted, provided that the above 37 * copyright notice and this permission notice appear in all copies. 38 * 39 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 40 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 41 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 42 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 43 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 44 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 45 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 46 */ 47 48 /* Based on $xFreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des Exp $ */ 49 #include "includes.h" 50 RCSID("$Id: auth-pam.c,v 1.128 2006/01/29 05:46:13 dtucker Exp $"); 51 RCSID("$FreeBSD$"); 52 53 #ifdef USE_PAM 54 #if defined(HAVE_SECURITY_PAM_APPL_H) 55 #include <security/pam_appl.h> 56 #elif defined (HAVE_PAM_PAM_APPL_H) 57 #include <pam/pam_appl.h> 58 #endif 59 60 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */ 61 #ifdef PAM_SUN_CODEBASE 62 # define sshpam_const /* Solaris, HP-UX, AIX */ 63 #else 64 # define sshpam_const const /* LinuxPAM, OpenPAM */ 65 #endif 66 67 #include "auth.h" 68 #include "auth-pam.h" 69 #include "buffer.h" 70 #include "bufaux.h" 71 #include "canohost.h" 72 #include "log.h" 73 #include "monitor_wrap.h" 74 #include "msg.h" 75 #include "packet.h" 76 #include "misc.h" 77 #include "servconf.h" 78 #include "ssh2.h" 79 #include "xmalloc.h" 80 #include "auth-options.h" 81 82 extern ServerOptions options; 83 extern Buffer loginmsg; 84 extern int compat20; 85 extern u_int utmp_len; 86 87 /* so we don't silently change behaviour */ 88 #ifdef USE_POSIX_THREADS 89 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK" 90 #endif 91 92 /* 93 * Formerly known as USE_POSIX_THREADS, using this is completely unsupported 94 * and generally a bad idea. Use at own risk and do not expect support if 95 * this breaks. 96 */ 97 #ifdef UNSUPPORTED_POSIX_THREADS_HACK 98 #include <pthread.h> 99 /* 100 * Avoid namespace clash when *not* using pthreads for systems *with* 101 * pthreads, which unconditionally define pthread_t via sys/types.h 102 * (e.g. Linux) 103 */ 104 typedef pthread_t sp_pthread_t; 105 #else 106 typedef pid_t sp_pthread_t; 107 #endif 108 109 struct pam_ctxt { 110 sp_pthread_t pam_thread; 111 int pam_psock; 112 int pam_csock; 113 int pam_done; 114 }; 115 116 static void sshpam_free_ctx(void *); 117 static struct pam_ctxt *cleanup_ctxt; 118 119 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 120 /* 121 * Simulate threads with processes. 122 */ 123 124 static int sshpam_thread_status = -1; 125 static mysig_t sshpam_oldsig; 126 127 static void 128 sshpam_sigchld_handler(int sig) 129 { 130 signal(SIGCHLD, SIG_DFL); 131 if (cleanup_ctxt == NULL) 132 return; /* handler called after PAM cleanup, shouldn't happen */ 133 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG) 134 <= 0) { 135 /* PAM thread has not exitted, privsep slave must have */ 136 kill(cleanup_ctxt->pam_thread, SIGTERM); 137 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, 0) 138 <= 0) 139 return; /* could not wait */ 140 } 141 if (WIFSIGNALED(sshpam_thread_status) && 142 WTERMSIG(sshpam_thread_status) == SIGTERM) 143 return; /* terminated by pthread_cancel */ 144 if (!WIFEXITED(sshpam_thread_status)) 145 fatal("PAM: authentication thread exited unexpectedly"); 146 if (WEXITSTATUS(sshpam_thread_status) != 0) 147 fatal("PAM: authentication thread exited uncleanly"); 148 } 149 150 static void 151 pthread_exit(void *value __unused) 152 { 153 _exit(0); 154 } 155 156 static int 157 pthread_create(sp_pthread_t *thread, const void *attr __unused, 158 void *(*thread_start)(void *), void *arg) 159 { 160 pid_t pid; 161 struct pam_ctxt *ctx = arg; 162 163 sshpam_thread_status = -1; 164 switch ((pid = fork())) { 165 case -1: 166 error("fork(): %s", strerror(errno)); 167 return (-1); 168 case 0: 169 close(ctx->pam_psock); 170 ctx->pam_psock = -1; 171 thread_start(arg); 172 _exit(1); 173 default: 174 *thread = pid; 175 close(ctx->pam_csock); 176 ctx->pam_csock = -1; 177 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler); 178 return (0); 179 } 180 } 181 182 static int 183 pthread_cancel(sp_pthread_t thread) 184 { 185 signal(SIGCHLD, sshpam_oldsig); 186 return (kill(thread, SIGTERM)); 187 } 188 189 static int 190 pthread_join(sp_pthread_t thread, void **value __unused) 191 { 192 int status; 193 194 if (sshpam_thread_status != -1) 195 return (sshpam_thread_status); 196 signal(SIGCHLD, sshpam_oldsig); 197 waitpid(thread, &status, 0); 198 return (status); 199 } 200 #endif 201 202 203 static pam_handle_t *sshpam_handle = NULL; 204 static int sshpam_err = 0; 205 static int sshpam_authenticated = 0; 206 static int sshpam_session_open = 0; 207 static int sshpam_cred_established = 0; 208 static int sshpam_account_status = -1; 209 static char **sshpam_env = NULL; 210 static Authctxt *sshpam_authctxt = NULL; 211 static const char *sshpam_password = NULL; 212 static char badpw[] = "\b\n\r\177INCORRECT"; 213 214 /* Some PAM implementations don't implement this */ 215 #ifndef HAVE_PAM_GETENVLIST 216 static char ** 217 pam_getenvlist(pam_handle_t *pamh) 218 { 219 /* 220 * XXX - If necessary, we can still support envrionment passing 221 * for platforms without pam_getenvlist by searching for known 222 * env vars (e.g. KRB5CCNAME) from the PAM environment. 223 */ 224 return NULL; 225 } 226 #endif 227 228 /* 229 * Some platforms, notably Solaris, do not enforce password complexity 230 * rules during pam_chauthtok() if the real uid of the calling process 231 * is 0, on the assumption that it's being called by "passwd" run by root. 232 * This wraps pam_chauthtok and sets/restore the real uid so PAM will do 233 * the right thing. 234 */ 235 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID 236 static int 237 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags) 238 { 239 int result; 240 241 if (sshpam_authctxt == NULL) 242 fatal("PAM: sshpam_authctxt not initialized"); 243 if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1) 244 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 245 result = pam_chauthtok(pamh, flags); 246 if (setreuid(0, -1) == -1) 247 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 248 return result; 249 } 250 # define pam_chauthtok(a,b) (sshpam_chauthtok_ruid((a), (b))) 251 #endif 252 253 void 254 sshpam_password_change_required(int reqd) 255 { 256 debug3("%s %d", __func__, reqd); 257 if (sshpam_authctxt == NULL) 258 fatal("%s: PAM authctxt not initialized", __func__); 259 sshpam_authctxt->force_pwchange = reqd; 260 if (reqd) { 261 no_port_forwarding_flag |= 2; 262 no_agent_forwarding_flag |= 2; 263 no_x11_forwarding_flag |= 2; 264 } else { 265 no_port_forwarding_flag &= ~2; 266 no_agent_forwarding_flag &= ~2; 267 no_x11_forwarding_flag &= ~2; 268 } 269 } 270 271 /* Import regular and PAM environment from subprocess */ 272 static void 273 import_environments(Buffer *b) 274 { 275 char *env; 276 u_int i, num_env; 277 int err; 278 279 debug3("PAM: %s entering", __func__); 280 281 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 282 /* Import variables set by do_pam_account */ 283 sshpam_account_status = buffer_get_int(b); 284 sshpam_password_change_required(buffer_get_int(b)); 285 286 /* Import environment from subprocess */ 287 num_env = buffer_get_int(b); 288 sshpam_env = xmalloc((num_env + 1) * sizeof(*sshpam_env)); 289 debug3("PAM: num env strings %d", num_env); 290 for(i = 0; i < num_env; i++) 291 sshpam_env[i] = buffer_get_string(b, NULL); 292 293 sshpam_env[num_env] = NULL; 294 295 /* Import PAM environment from subprocess */ 296 num_env = buffer_get_int(b); 297 debug("PAM: num PAM env strings %d", num_env); 298 for(i = 0; i < num_env; i++) { 299 env = buffer_get_string(b, NULL); 300 301 #ifdef HAVE_PAM_PUTENV 302 /* Errors are not fatal here */ 303 if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) { 304 error("PAM: pam_putenv: %s", 305 pam_strerror(sshpam_handle, sshpam_err)); 306 } 307 #endif 308 } 309 #endif 310 } 311 312 /* 313 * Conversation function for authentication thread. 314 */ 315 static int 316 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg, 317 struct pam_response **resp, void *data) 318 { 319 Buffer buffer; 320 struct pam_ctxt *ctxt; 321 struct pam_response *reply; 322 int i; 323 324 debug3("PAM: %s entering, %d messages", __func__, n); 325 *resp = NULL; 326 327 if (data == NULL) { 328 error("PAM: conversation function passed a null context"); 329 return (PAM_CONV_ERR); 330 } 331 ctxt = data; 332 if (n <= 0 || n > PAM_MAX_NUM_MSG) 333 return (PAM_CONV_ERR); 334 335 if ((reply = malloc(n * sizeof(*reply))) == NULL) 336 return (PAM_CONV_ERR); 337 memset(reply, 0, n * sizeof(*reply)); 338 339 buffer_init(&buffer); 340 for (i = 0; i < n; ++i) { 341 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 342 case PAM_PROMPT_ECHO_OFF: 343 buffer_put_cstring(&buffer, 344 PAM_MSG_MEMBER(msg, i, msg)); 345 if (ssh_msg_send(ctxt->pam_csock, 346 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1) 347 goto fail; 348 if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1) 349 goto fail; 350 if (buffer_get_char(&buffer) != PAM_AUTHTOK) 351 goto fail; 352 reply[i].resp = buffer_get_string(&buffer, NULL); 353 break; 354 case PAM_PROMPT_ECHO_ON: 355 buffer_put_cstring(&buffer, 356 PAM_MSG_MEMBER(msg, i, msg)); 357 if (ssh_msg_send(ctxt->pam_csock, 358 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1) 359 goto fail; 360 if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1) 361 goto fail; 362 if (buffer_get_char(&buffer) != PAM_AUTHTOK) 363 goto fail; 364 reply[i].resp = buffer_get_string(&buffer, NULL); 365 break; 366 case PAM_ERROR_MSG: 367 buffer_put_cstring(&buffer, 368 PAM_MSG_MEMBER(msg, i, msg)); 369 if (ssh_msg_send(ctxt->pam_csock, 370 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1) 371 goto fail; 372 break; 373 case PAM_TEXT_INFO: 374 buffer_put_cstring(&buffer, 375 PAM_MSG_MEMBER(msg, i, msg)); 376 if (ssh_msg_send(ctxt->pam_csock, 377 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1) 378 goto fail; 379 break; 380 default: 381 goto fail; 382 } 383 buffer_clear(&buffer); 384 } 385 buffer_free(&buffer); 386 *resp = reply; 387 return (PAM_SUCCESS); 388 389 fail: 390 for(i = 0; i < n; i++) { 391 if (reply[i].resp != NULL) 392 xfree(reply[i].resp); 393 } 394 xfree(reply); 395 buffer_free(&buffer); 396 return (PAM_CONV_ERR); 397 } 398 399 /* 400 * Authentication thread. 401 */ 402 static void * 403 sshpam_thread(void *ctxtp) 404 { 405 struct pam_ctxt *ctxt = ctxtp; 406 Buffer buffer; 407 struct pam_conv sshpam_conv; 408 int flags = (options.permit_empty_passwd == 0 ? 409 PAM_DISALLOW_NULL_AUTHTOK : 0); 410 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 411 extern char **environ; 412 char **env_from_pam; 413 u_int i; 414 const char *pam_user; 415 const char **ptr_pam_user = &pam_user; 416 417 pam_get_item(sshpam_handle, PAM_USER, 418 (sshpam_const void **)ptr_pam_user); 419 environ[0] = NULL; 420 421 if (sshpam_authctxt != NULL) { 422 setproctitle("%s [pam]", 423 sshpam_authctxt->valid ? pam_user : "unknown"); 424 } 425 #endif 426 427 sshpam_conv.conv = sshpam_thread_conv; 428 sshpam_conv.appdata_ptr = ctxt; 429 430 if (sshpam_authctxt == NULL) 431 fatal("%s: PAM authctxt not initialized", __func__); 432 433 buffer_init(&buffer); 434 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 435 (const void *)&sshpam_conv); 436 if (sshpam_err != PAM_SUCCESS) 437 goto auth_fail; 438 sshpam_err = pam_authenticate(sshpam_handle, flags); 439 if (sshpam_err != PAM_SUCCESS) 440 goto auth_fail; 441 442 if (compat20) { 443 if (!do_pam_account()) 444 goto auth_fail; 445 if (sshpam_authctxt->force_pwchange) { 446 sshpam_err = pam_chauthtok(sshpam_handle, 447 PAM_CHANGE_EXPIRED_AUTHTOK); 448 if (sshpam_err != PAM_SUCCESS) 449 goto auth_fail; 450 sshpam_password_change_required(0); 451 } 452 } 453 454 buffer_put_cstring(&buffer, "OK"); 455 456 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 457 /* Export variables set by do_pam_account */ 458 buffer_put_int(&buffer, sshpam_account_status); 459 buffer_put_int(&buffer, sshpam_authctxt->force_pwchange); 460 461 /* Export any environment strings set in child */ 462 for(i = 0; environ[i] != NULL; i++) 463 ; /* Count */ 464 buffer_put_int(&buffer, i); 465 for(i = 0; environ[i] != NULL; i++) 466 buffer_put_cstring(&buffer, environ[i]); 467 468 /* Export any environment strings set by PAM in child */ 469 env_from_pam = pam_getenvlist(sshpam_handle); 470 for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) 471 ; /* Count */ 472 buffer_put_int(&buffer, i); 473 for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) 474 buffer_put_cstring(&buffer, env_from_pam[i]); 475 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */ 476 477 /* XXX - can't do much about an error here */ 478 ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer); 479 buffer_free(&buffer); 480 pthread_exit(NULL); 481 482 auth_fail: 483 buffer_put_cstring(&buffer, 484 pam_strerror(sshpam_handle, sshpam_err)); 485 /* XXX - can't do much about an error here */ 486 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer); 487 buffer_free(&buffer); 488 pthread_exit(NULL); 489 490 return (NULL); /* Avoid warning for non-pthread case */ 491 } 492 493 void 494 sshpam_thread_cleanup(void) 495 { 496 struct pam_ctxt *ctxt = cleanup_ctxt; 497 498 debug3("PAM: %s entering", __func__); 499 if (ctxt != NULL && ctxt->pam_thread != 0) { 500 pthread_cancel(ctxt->pam_thread); 501 pthread_join(ctxt->pam_thread, NULL); 502 close(ctxt->pam_psock); 503 close(ctxt->pam_csock); 504 memset(ctxt, 0, sizeof(*ctxt)); 505 cleanup_ctxt = NULL; 506 } 507 } 508 509 static int 510 sshpam_null_conv(int n, sshpam_const struct pam_message **msg, 511 struct pam_response **resp, void *data) 512 { 513 debug3("PAM: %s entering, %d messages", __func__, n); 514 return (PAM_CONV_ERR); 515 } 516 517 static struct pam_conv null_conv = { sshpam_null_conv, NULL }; 518 519 static int 520 sshpam_store_conv(int n, sshpam_const struct pam_message **msg, 521 struct pam_response **resp, void *data) 522 { 523 struct pam_response *reply; 524 int i; 525 size_t len; 526 527 debug3("PAM: %s called with %d messages", __func__, n); 528 *resp = NULL; 529 530 if (n <= 0 || n > PAM_MAX_NUM_MSG) 531 return (PAM_CONV_ERR); 532 533 if ((reply = malloc(n * sizeof(*reply))) == NULL) 534 return (PAM_CONV_ERR); 535 memset(reply, 0, n * sizeof(*reply)); 536 537 for (i = 0; i < n; ++i) { 538 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 539 case PAM_ERROR_MSG: 540 case PAM_TEXT_INFO: 541 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 542 buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len); 543 buffer_append(&loginmsg, "\n", 1 ); 544 reply[i].resp_retcode = PAM_SUCCESS; 545 break; 546 default: 547 goto fail; 548 } 549 } 550 *resp = reply; 551 return (PAM_SUCCESS); 552 553 fail: 554 for(i = 0; i < n; i++) { 555 if (reply[i].resp != NULL) 556 xfree(reply[i].resp); 557 } 558 xfree(reply); 559 return (PAM_CONV_ERR); 560 } 561 562 static struct pam_conv store_conv = { sshpam_store_conv, NULL }; 563 564 void 565 sshpam_cleanup(void) 566 { 567 debug("PAM: cleanup"); 568 if (sshpam_handle == NULL) 569 return; 570 pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv); 571 if (sshpam_cred_established) { 572 pam_setcred(sshpam_handle, PAM_DELETE_CRED); 573 sshpam_cred_established = 0; 574 } 575 if (sshpam_session_open) { 576 pam_close_session(sshpam_handle, PAM_SILENT); 577 sshpam_session_open = 0; 578 } 579 sshpam_authenticated = 0; 580 pam_end(sshpam_handle, sshpam_err); 581 sshpam_handle = NULL; 582 } 583 584 static int 585 sshpam_init(Authctxt *authctxt) 586 { 587 extern char *__progname; 588 const char *pam_rhost, *pam_user, *user = authctxt->user; 589 const char **ptr_pam_user = &pam_user; 590 591 if (sshpam_handle != NULL) { 592 /* We already have a PAM context; check if the user matches */ 593 sshpam_err = pam_get_item(sshpam_handle, 594 PAM_USER, (sshpam_const void **)ptr_pam_user); 595 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0) 596 return (0); 597 pam_end(sshpam_handle, sshpam_err); 598 sshpam_handle = NULL; 599 } 600 debug("PAM: initializing for \"%s\"", user); 601 sshpam_err = 602 pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle); 603 sshpam_authctxt = authctxt; 604 605 if (sshpam_err != PAM_SUCCESS) { 606 pam_end(sshpam_handle, sshpam_err); 607 sshpam_handle = NULL; 608 return (-1); 609 } 610 pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns); 611 debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost); 612 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost); 613 if (sshpam_err != PAM_SUCCESS) { 614 pam_end(sshpam_handle, sshpam_err); 615 sshpam_handle = NULL; 616 return (-1); 617 } 618 #ifdef PAM_TTY_KLUDGE 619 /* 620 * Some silly PAM modules (e.g. pam_time) require a TTY to operate. 621 * sshd doesn't set the tty until too late in the auth process and 622 * may not even set one (for tty-less connections) 623 */ 624 debug("PAM: setting PAM_TTY to \"ssh\""); 625 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh"); 626 if (sshpam_err != PAM_SUCCESS) { 627 pam_end(sshpam_handle, sshpam_err); 628 sshpam_handle = NULL; 629 return (-1); 630 } 631 #endif 632 return (0); 633 } 634 635 static void * 636 sshpam_init_ctx(Authctxt *authctxt) 637 { 638 struct pam_ctxt *ctxt; 639 int socks[2]; 640 641 debug3("PAM: %s entering", __func__); 642 /* Refuse to start if we don't have PAM enabled */ 643 if (!options.use_pam) 644 return NULL; 645 646 /* Initialize PAM */ 647 if (sshpam_init(authctxt) == -1) { 648 error("PAM: initialization failed"); 649 return (NULL); 650 } 651 652 ctxt = xmalloc(sizeof *ctxt); 653 memset(ctxt, 0, sizeof(*ctxt)); 654 655 /* Start the authentication thread */ 656 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) { 657 error("PAM: failed create sockets: %s", strerror(errno)); 658 xfree(ctxt); 659 return (NULL); 660 } 661 ctxt->pam_psock = socks[0]; 662 ctxt->pam_csock = socks[1]; 663 if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) { 664 error("PAM: failed to start authentication thread: %s", 665 strerror(errno)); 666 close(socks[0]); 667 close(socks[1]); 668 xfree(ctxt); 669 return (NULL); 670 } 671 cleanup_ctxt = ctxt; 672 return (ctxt); 673 } 674 675 static int 676 sshpam_query(void *ctx, char **name, char **info, 677 u_int *num, char ***prompts, u_int **echo_on) 678 { 679 Buffer buffer; 680 struct pam_ctxt *ctxt = ctx; 681 size_t plen; 682 u_char type; 683 char *msg; 684 size_t len, mlen; 685 686 debug3("PAM: %s entering", __func__); 687 buffer_init(&buffer); 688 *name = xstrdup(""); 689 *info = xstrdup(""); 690 *prompts = xmalloc(sizeof(char *)); 691 **prompts = NULL; 692 plen = 0; 693 *echo_on = xmalloc(sizeof(u_int)); 694 while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) { 695 type = buffer_get_char(&buffer); 696 msg = buffer_get_string(&buffer, NULL); 697 mlen = strlen(msg); 698 switch (type) { 699 case PAM_PROMPT_ECHO_ON: 700 case PAM_PROMPT_ECHO_OFF: 701 *num = 1; 702 len = plen + mlen + 1; 703 **prompts = xrealloc(**prompts, len); 704 strlcpy(**prompts + plen, msg, len - plen); 705 plen += mlen; 706 **echo_on = (type == PAM_PROMPT_ECHO_ON); 707 xfree(msg); 708 return (0); 709 case PAM_ERROR_MSG: 710 case PAM_TEXT_INFO: 711 /* accumulate messages */ 712 len = plen + mlen + 2; 713 **prompts = xrealloc(**prompts, len); 714 strlcpy(**prompts + plen, msg, len - plen); 715 plen += mlen; 716 strlcat(**prompts + plen, "\n", len - plen); 717 plen++; 718 xfree(msg); 719 break; 720 case PAM_AUTH_ERR: 721 debug3("PAM: PAM_AUTH_ERR"); 722 if (**prompts != NULL && strlen(**prompts) != 0) { 723 *info = **prompts; 724 **prompts = NULL; 725 *num = 0; 726 **echo_on = 0; 727 ctxt->pam_done = -1; 728 return 0; 729 } 730 /* FALLTHROUGH */ 731 case PAM_SUCCESS: 732 if (**prompts != NULL) { 733 /* drain any accumulated messages */ 734 debug("PAM: %s", **prompts); 735 buffer_append(&loginmsg, **prompts, 736 strlen(**prompts)); 737 xfree(**prompts); 738 **prompts = NULL; 739 } 740 if (type == PAM_SUCCESS) { 741 if (!sshpam_authctxt->valid || 742 (sshpam_authctxt->pw->pw_uid == 0 && 743 options.permit_root_login != PERMIT_YES)) 744 fatal("Internal error: PAM auth " 745 "succeeded when it should have " 746 "failed"); 747 import_environments(&buffer); 748 *num = 0; 749 **echo_on = 0; 750 ctxt->pam_done = 1; 751 xfree(msg); 752 return (0); 753 } 754 error("PAM: %s for %s%.100s from %.100s", msg, 755 sshpam_authctxt->valid ? "" : "illegal user ", 756 sshpam_authctxt->user, 757 get_remote_name_or_ip(utmp_len, options.use_dns)); 758 /* FALLTHROUGH */ 759 default: 760 *num = 0; 761 **echo_on = 0; 762 xfree(msg); 763 ctxt->pam_done = -1; 764 return (-1); 765 } 766 } 767 return (-1); 768 } 769 770 /* XXX - see also comment in auth-chall.c:verify_response */ 771 static int 772 sshpam_respond(void *ctx, u_int num, char **resp) 773 { 774 Buffer buffer; 775 struct pam_ctxt *ctxt = ctx; 776 777 debug2("PAM: %s entering, %u responses", __func__, num); 778 switch (ctxt->pam_done) { 779 case 1: 780 sshpam_authenticated = 1; 781 return (0); 782 case 0: 783 break; 784 default: 785 return (-1); 786 } 787 if (num != 1) { 788 error("PAM: expected one response, got %u", num); 789 return (-1); 790 } 791 buffer_init(&buffer); 792 if (sshpam_authctxt->valid && 793 (sshpam_authctxt->pw->pw_uid != 0 || 794 options.permit_root_login == PERMIT_YES)) 795 buffer_put_cstring(&buffer, *resp); 796 else 797 buffer_put_cstring(&buffer, badpw); 798 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) { 799 buffer_free(&buffer); 800 return (-1); 801 } 802 buffer_free(&buffer); 803 return (1); 804 } 805 806 static void 807 sshpam_free_ctx(void *ctxtp) 808 { 809 struct pam_ctxt *ctxt = ctxtp; 810 811 debug3("PAM: %s entering", __func__); 812 sshpam_thread_cleanup(); 813 xfree(ctxt); 814 /* 815 * We don't call sshpam_cleanup() here because we may need the PAM 816 * handle at a later stage, e.g. when setting up a session. It's 817 * still on the cleanup list, so pam_end() *will* be called before 818 * the server process terminates. 819 */ 820 } 821 822 KbdintDevice sshpam_device = { 823 "pam", 824 sshpam_init_ctx, 825 sshpam_query, 826 sshpam_respond, 827 sshpam_free_ctx 828 }; 829 830 KbdintDevice mm_sshpam_device = { 831 "pam", 832 mm_sshpam_init_ctx, 833 mm_sshpam_query, 834 mm_sshpam_respond, 835 mm_sshpam_free_ctx 836 }; 837 838 /* 839 * This replaces auth-pam.c 840 */ 841 void 842 start_pam(Authctxt *authctxt) 843 { 844 if (!options.use_pam) 845 fatal("PAM: initialisation requested when UsePAM=no"); 846 847 if (sshpam_init(authctxt) == -1) 848 fatal("PAM: initialisation failed"); 849 } 850 851 void 852 finish_pam(void) 853 { 854 sshpam_cleanup(); 855 } 856 857 u_int 858 do_pam_account(void) 859 { 860 debug("%s: called", __func__); 861 if (sshpam_account_status != -1) 862 return (sshpam_account_status); 863 864 sshpam_err = pam_acct_mgmt(sshpam_handle, 0); 865 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err, 866 pam_strerror(sshpam_handle, sshpam_err)); 867 868 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) { 869 sshpam_account_status = 0; 870 return (sshpam_account_status); 871 } 872 873 if (sshpam_err == PAM_NEW_AUTHTOK_REQD) 874 sshpam_password_change_required(1); 875 876 sshpam_account_status = 1; 877 return (sshpam_account_status); 878 } 879 880 void 881 do_pam_set_tty(const char *tty) 882 { 883 if (tty != NULL) { 884 debug("PAM: setting PAM_TTY to \"%s\"", tty); 885 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty); 886 if (sshpam_err != PAM_SUCCESS) 887 fatal("PAM: failed to set PAM_TTY: %s", 888 pam_strerror(sshpam_handle, sshpam_err)); 889 } 890 } 891 892 void 893 do_pam_setcred(int init) 894 { 895 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 896 (const void *)&store_conv); 897 if (sshpam_err != PAM_SUCCESS) 898 fatal("PAM: failed to set PAM_CONV: %s", 899 pam_strerror(sshpam_handle, sshpam_err)); 900 if (init) { 901 debug("PAM: establishing credentials"); 902 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED); 903 } else { 904 debug("PAM: reinitializing credentials"); 905 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED); 906 } 907 if (sshpam_err == PAM_SUCCESS) { 908 sshpam_cred_established = 1; 909 return; 910 } 911 if (sshpam_authenticated) 912 fatal("PAM: pam_setcred(): %s", 913 pam_strerror(sshpam_handle, sshpam_err)); 914 else 915 debug("PAM: pam_setcred(): %s", 916 pam_strerror(sshpam_handle, sshpam_err)); 917 } 918 919 static int 920 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg, 921 struct pam_response **resp, void *data) 922 { 923 char input[PAM_MAX_MSG_SIZE]; 924 struct pam_response *reply; 925 int i; 926 927 debug3("PAM: %s called with %d messages", __func__, n); 928 929 *resp = NULL; 930 931 if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO)) 932 return (PAM_CONV_ERR); 933 934 if ((reply = malloc(n * sizeof(*reply))) == NULL) 935 return (PAM_CONV_ERR); 936 memset(reply, 0, n * sizeof(*reply)); 937 938 for (i = 0; i < n; ++i) { 939 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 940 case PAM_PROMPT_ECHO_OFF: 941 reply[i].resp = 942 read_passphrase(PAM_MSG_MEMBER(msg, i, msg), 943 RP_ALLOW_STDIN); 944 reply[i].resp_retcode = PAM_SUCCESS; 945 break; 946 case PAM_PROMPT_ECHO_ON: 947 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 948 fgets(input, sizeof input, stdin); 949 if ((reply[i].resp = strdup(input)) == NULL) 950 goto fail; 951 reply[i].resp_retcode = PAM_SUCCESS; 952 break; 953 case PAM_ERROR_MSG: 954 case PAM_TEXT_INFO: 955 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 956 reply[i].resp_retcode = PAM_SUCCESS; 957 break; 958 default: 959 goto fail; 960 } 961 } 962 *resp = reply; 963 return (PAM_SUCCESS); 964 965 fail: 966 for(i = 0; i < n; i++) { 967 if (reply[i].resp != NULL) 968 xfree(reply[i].resp); 969 } 970 xfree(reply); 971 return (PAM_CONV_ERR); 972 } 973 974 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL }; 975 976 /* 977 * XXX this should be done in the authentication phase, but ssh1 doesn't 978 * support that 979 */ 980 void 981 do_pam_chauthtok(void) 982 { 983 if (use_privsep) 984 fatal("Password expired (unable to change with privsep)"); 985 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 986 (const void *)&tty_conv); 987 if (sshpam_err != PAM_SUCCESS) 988 fatal("PAM: failed to set PAM_CONV: %s", 989 pam_strerror(sshpam_handle, sshpam_err)); 990 debug("PAM: changing password"); 991 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK); 992 if (sshpam_err != PAM_SUCCESS) 993 fatal("PAM: pam_chauthtok(): %s", 994 pam_strerror(sshpam_handle, sshpam_err)); 995 } 996 997 void 998 do_pam_session(void) 999 { 1000 debug3("PAM: opening session"); 1001 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1002 (const void *)&store_conv); 1003 if (sshpam_err != PAM_SUCCESS) 1004 fatal("PAM: failed to set PAM_CONV: %s", 1005 pam_strerror(sshpam_handle, sshpam_err)); 1006 sshpam_err = pam_open_session(sshpam_handle, 0); 1007 if (sshpam_err == PAM_SUCCESS) 1008 sshpam_session_open = 1; 1009 else { 1010 sshpam_session_open = 0; 1011 disable_forwarding(); 1012 error("PAM: pam_open_session(): %s", 1013 pam_strerror(sshpam_handle, sshpam_err)); 1014 } 1015 1016 } 1017 1018 int 1019 is_pam_session_open(void) 1020 { 1021 return sshpam_session_open; 1022 } 1023 1024 /* 1025 * Set a PAM environment string. We need to do this so that the session 1026 * modules can handle things like Kerberos/GSI credentials that appear 1027 * during the ssh authentication process. 1028 */ 1029 int 1030 do_pam_putenv(char *name, char *value) 1031 { 1032 int ret = 1; 1033 #ifdef HAVE_PAM_PUTENV 1034 char *compound; 1035 size_t len; 1036 1037 len = strlen(name) + strlen(value) + 2; 1038 compound = xmalloc(len); 1039 1040 snprintf(compound, len, "%s=%s", name, value); 1041 ret = pam_putenv(sshpam_handle, compound); 1042 xfree(compound); 1043 #endif 1044 1045 return (ret); 1046 } 1047 1048 char ** 1049 fetch_pam_child_environment(void) 1050 { 1051 return sshpam_env; 1052 } 1053 1054 char ** 1055 fetch_pam_environment(void) 1056 { 1057 return (pam_getenvlist(sshpam_handle)); 1058 } 1059 1060 void 1061 free_pam_environment(char **env) 1062 { 1063 char **envp; 1064 1065 if (env == NULL) 1066 return; 1067 1068 for (envp = env; *envp; envp++) 1069 xfree(*envp); 1070 xfree(env); 1071 } 1072 1073 /* 1074 * "Blind" conversation function for password authentication. Assumes that 1075 * echo-off prompts are for the password and stores messages for later 1076 * display. 1077 */ 1078 static int 1079 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg, 1080 struct pam_response **resp, void *data) 1081 { 1082 struct pam_response *reply; 1083 int i; 1084 size_t len; 1085 1086 debug3("PAM: %s called with %d messages", __func__, n); 1087 1088 *resp = NULL; 1089 1090 if (n <= 0 || n > PAM_MAX_NUM_MSG) 1091 return (PAM_CONV_ERR); 1092 1093 if ((reply = malloc(n * sizeof(*reply))) == NULL) 1094 return (PAM_CONV_ERR); 1095 memset(reply, 0, n * sizeof(*reply)); 1096 1097 for (i = 0; i < n; ++i) { 1098 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1099 case PAM_PROMPT_ECHO_OFF: 1100 if (sshpam_password == NULL) 1101 goto fail; 1102 if ((reply[i].resp = strdup(sshpam_password)) == NULL) 1103 goto fail; 1104 reply[i].resp_retcode = PAM_SUCCESS; 1105 break; 1106 case PAM_ERROR_MSG: 1107 case PAM_TEXT_INFO: 1108 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 1109 if (len > 0) { 1110 buffer_append(&loginmsg, 1111 PAM_MSG_MEMBER(msg, i, msg), len); 1112 buffer_append(&loginmsg, "\n", 1); 1113 } 1114 if ((reply[i].resp = strdup("")) == NULL) 1115 goto fail; 1116 reply[i].resp_retcode = PAM_SUCCESS; 1117 break; 1118 default: 1119 goto fail; 1120 } 1121 } 1122 *resp = reply; 1123 return (PAM_SUCCESS); 1124 1125 fail: 1126 for(i = 0; i < n; i++) { 1127 if (reply[i].resp != NULL) 1128 xfree(reply[i].resp); 1129 } 1130 xfree(reply); 1131 return (PAM_CONV_ERR); 1132 } 1133 1134 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL }; 1135 1136 /* 1137 * Attempt password authentication via PAM 1138 */ 1139 int 1140 sshpam_auth_passwd(Authctxt *authctxt, const char *password) 1141 { 1142 int flags = (options.permit_empty_passwd == 0 ? 1143 PAM_DISALLOW_NULL_AUTHTOK : 0); 1144 1145 if (!options.use_pam || sshpam_handle == NULL) 1146 fatal("PAM: %s called when PAM disabled or failed to " 1147 "initialise.", __func__); 1148 1149 sshpam_password = password; 1150 sshpam_authctxt = authctxt; 1151 1152 /* 1153 * If the user logging in is invalid, or is root but is not permitted 1154 * by PermitRootLogin, use an invalid password to prevent leaking 1155 * information via timing (eg if the PAM config has a delay on fail). 1156 */ 1157 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 && 1158 options.permit_root_login != PERMIT_YES)) 1159 sshpam_password = badpw; 1160 1161 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1162 (const void *)&passwd_conv); 1163 if (sshpam_err != PAM_SUCCESS) 1164 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__, 1165 pam_strerror(sshpam_handle, sshpam_err)); 1166 1167 sshpam_err = pam_authenticate(sshpam_handle, flags); 1168 sshpam_password = NULL; 1169 if (sshpam_err == PAM_SUCCESS && authctxt->valid) { 1170 debug("PAM: password authentication accepted for %.100s", 1171 authctxt->user); 1172 return 1; 1173 } else { 1174 debug("PAM: password authentication failed for %.100s: %s", 1175 authctxt->valid ? authctxt->user : "an illegal user", 1176 pam_strerror(sshpam_handle, sshpam_err)); 1177 return 0; 1178 } 1179 } 1180 #endif /* USE_PAM */ 1181