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 (at) mindrot.org> 33 * Copyright (c) 2003,2004 Darren Tucker <dtucker (at) 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 $FreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des Exp $ */ 49 #include "includes.h" 50 51 #include <sys/types.h> 52 #include <sys/stat.h> 53 #include <sys/wait.h> 54 55 #include <errno.h> 56 #include <signal.h> 57 #include <stdarg.h> 58 #include <string.h> 59 #include <unistd.h> 60 61 #ifdef USE_PAM 62 #if defined(HAVE_SECURITY_PAM_APPL_H) 63 #include <security/pam_appl.h> 64 #elif defined (HAVE_PAM_PAM_APPL_H) 65 #include <pam/pam_appl.h> 66 #endif 67 68 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */ 69 #ifdef PAM_SUN_CODEBASE 70 # define sshpam_const /* Solaris, HP-UX, AIX */ 71 #else 72 # define sshpam_const const /* LinuxPAM, OpenPAM */ 73 #endif 74 75 /* Ambiguity in spec: is it an array of pointers or a pointer to an array? */ 76 #ifdef PAM_SUN_CODEBASE 77 # define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member) 78 #else 79 # define PAM_MSG_MEMBER(msg, n, member) ((msg)[(n)]->member) 80 #endif 81 82 #include "xmalloc.h" 83 #include "buffer.h" 84 #include "key.h" 85 #include "hostfile.h" 86 #include "auth.h" 87 #include "auth-pam.h" 88 #include "canohost.h" 89 #include "log.h" 90 #include "msg.h" 91 #include "packet.h" 92 #include "misc.h" 93 #include "servconf.h" 94 #include "ssh2.h" 95 #include "auth-options.h" 96 #ifdef GSSAPI 97 #include "ssh-gss.h" 98 #endif 99 #include "monitor_wrap.h" 100 101 extern ServerOptions options; 102 extern Buffer loginmsg; 103 extern int compat20; 104 extern u_int utmp_len; 105 106 /* so we don't silently change behaviour */ 107 #ifdef USE_POSIX_THREADS 108 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK" 109 #endif 110 111 /* 112 * Formerly known as USE_POSIX_THREADS, using this is completely unsupported 113 * and generally a bad idea. Use at own risk and do not expect support if 114 * this breaks. 115 */ 116 #ifdef UNSUPPORTED_POSIX_THREADS_HACK 117 #include <pthread.h> 118 /* 119 * Avoid namespace clash when *not* using pthreads for systems *with* 120 * pthreads, which unconditionally define pthread_t via sys/types.h 121 * (e.g. Linux) 122 */ 123 typedef pthread_t sp_pthread_t; 124 #else 125 typedef pid_t sp_pthread_t; 126 #endif 127 128 struct pam_ctxt { 129 sp_pthread_t pam_thread; 130 int pam_psock; 131 int pam_csock; 132 int pam_done; 133 }; 134 135 static void sshpam_free_ctx(void *); 136 static struct pam_ctxt *cleanup_ctxt; 137 138 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 139 /* 140 * Simulate threads with processes. 141 */ 142 143 static int sshpam_thread_status = -1; 144 static mysig_t sshpam_oldsig; 145 146 static void 147 sshpam_sigchld_handler(int sig) 148 { 149 signal(SIGCHLD, SIG_DFL); 150 if (cleanup_ctxt == NULL) 151 return; /* handler called after PAM cleanup, shouldn't happen */ 152 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG) 153 <= 0) { 154 /* PAM thread has not exitted, privsep slave must have */ 155 kill(cleanup_ctxt->pam_thread, SIGTERM); 156 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, 0) 157 <= 0) 158 return; /* could not wait */ 159 } 160 if (WIFSIGNALED(sshpam_thread_status) && 161 WTERMSIG(sshpam_thread_status) == SIGTERM) 162 return; /* terminated by pthread_cancel */ 163 if (!WIFEXITED(sshpam_thread_status)) 164 sigdie("PAM: authentication thread exited unexpectedly"); 165 if (WEXITSTATUS(sshpam_thread_status) != 0) 166 sigdie("PAM: authentication thread exited uncleanly"); 167 } 168 169 /* ARGSUSED */ 170 static void 171 pthread_exit(void *value) 172 { 173 _exit(0); 174 } 175 176 /* ARGSUSED */ 177 static int 178 pthread_create(sp_pthread_t *thread, const void *attr, 179 void *(*thread_start)(void *), void *arg) 180 { 181 pid_t pid; 182 struct pam_ctxt *ctx = arg; 183 184 sshpam_thread_status = -1; 185 switch ((pid = fork())) { 186 case -1: 187 error("fork(): %s", strerror(errno)); 188 return (-1); 189 case 0: 190 close(ctx->pam_psock); 191 ctx->pam_psock = -1; 192 thread_start(arg); 193 _exit(1); 194 default: 195 *thread = pid; 196 close(ctx->pam_csock); 197 ctx->pam_csock = -1; 198 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler); 199 return (0); 200 } 201 } 202 203 static int 204 pthread_cancel(sp_pthread_t thread) 205 { 206 signal(SIGCHLD, sshpam_oldsig); 207 return (kill(thread, SIGTERM)); 208 } 209 210 /* ARGSUSED */ 211 static int 212 pthread_join(sp_pthread_t thread, void **value) 213 { 214 int status; 215 216 if (sshpam_thread_status != -1) 217 return (sshpam_thread_status); 218 signal(SIGCHLD, sshpam_oldsig); 219 waitpid(thread, &status, 0); 220 return (status); 221 } 222 #endif 223 224 225 static pam_handle_t *sshpam_handle = NULL; 226 static int sshpam_err = 0; 227 static int sshpam_authenticated = 0; 228 static int sshpam_session_open = 0; 229 static int sshpam_cred_established = 0; 230 static int sshpam_account_status = -1; 231 static char **sshpam_env = NULL; 232 static Authctxt *sshpam_authctxt = NULL; 233 static const char *sshpam_password = NULL; 234 static char badpw[] = "\b\n\r\177INCORRECT"; 235 236 /* Some PAM implementations don't implement this */ 237 #ifndef HAVE_PAM_GETENVLIST 238 static char ** 239 pam_getenvlist(pam_handle_t *pamh) 240 { 241 /* 242 * XXX - If necessary, we can still support envrionment passing 243 * for platforms without pam_getenvlist by searching for known 244 * env vars (e.g. KRB5CCNAME) from the PAM environment. 245 */ 246 return NULL; 247 } 248 #endif 249 250 /* 251 * Some platforms, notably Solaris, do not enforce password complexity 252 * rules during pam_chauthtok() if the real uid of the calling process 253 * is 0, on the assumption that it's being called by "passwd" run by root. 254 * This wraps pam_chauthtok and sets/restore the real uid so PAM will do 255 * the right thing. 256 */ 257 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID 258 static int 259 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags) 260 { 261 int result; 262 263 if (sshpam_authctxt == NULL) 264 fatal("PAM: sshpam_authctxt not initialized"); 265 if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1) 266 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 267 result = pam_chauthtok(pamh, flags); 268 if (setreuid(0, -1) == -1) 269 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 270 return result; 271 } 272 # define pam_chauthtok(a,b) (sshpam_chauthtok_ruid((a), (b))) 273 #endif 274 275 void 276 sshpam_password_change_required(int reqd) 277 { 278 debug3("%s %d", __func__, reqd); 279 if (sshpam_authctxt == NULL) 280 fatal("%s: PAM authctxt not initialized", __func__); 281 sshpam_authctxt->force_pwchange = reqd; 282 if (reqd) { 283 no_port_forwarding_flag |= 2; 284 no_agent_forwarding_flag |= 2; 285 no_x11_forwarding_flag |= 2; 286 } else { 287 no_port_forwarding_flag &= ~2; 288 no_agent_forwarding_flag &= ~2; 289 no_x11_forwarding_flag &= ~2; 290 } 291 } 292 293 /* Import regular and PAM environment from subprocess */ 294 static void 295 import_environments(Buffer *b) 296 { 297 char *env; 298 u_int i, num_env; 299 int err; 300 301 debug3("PAM: %s entering", __func__); 302 303 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 304 /* Import variables set by do_pam_account */ 305 sshpam_account_status = buffer_get_int(b); 306 sshpam_password_change_required(buffer_get_int(b)); 307 308 /* Import environment from subprocess */ 309 num_env = buffer_get_int(b); 310 if (num_env > 1024) 311 fatal("%s: received %u environment variables, expected <= 1024", 312 __func__, num_env); 313 sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env)); 314 debug3("PAM: num env strings %d", num_env); 315 for(i = 0; i < num_env; i++) 316 sshpam_env[i] = buffer_get_string(b, NULL); 317 318 sshpam_env[num_env] = NULL; 319 320 /* Import PAM environment from subprocess */ 321 num_env = buffer_get_int(b); 322 debug("PAM: num PAM env strings %d", num_env); 323 for(i = 0; i < num_env; i++) { 324 env = buffer_get_string(b, NULL); 325 326 #ifdef HAVE_PAM_PUTENV 327 /* Errors are not fatal here */ 328 if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) { 329 error("PAM: pam_putenv: %s", 330 pam_strerror(sshpam_handle, sshpam_err)); 331 } 332 #endif 333 } 334 #endif 335 } 336 337 /* 338 * Conversation function for authentication thread. 339 */ 340 static int 341 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg, 342 struct pam_response **resp, void *data) 343 { 344 Buffer buffer; 345 struct pam_ctxt *ctxt; 346 struct pam_response *reply; 347 int i; 348 349 debug3("PAM: %s entering, %d messages", __func__, n); 350 *resp = NULL; 351 352 if (data == NULL) { 353 error("PAM: conversation function passed a null context"); 354 return (PAM_CONV_ERR); 355 } 356 ctxt = data; 357 if (n <= 0 || n > PAM_MAX_NUM_MSG) 358 return (PAM_CONV_ERR); 359 360 if ((reply = calloc(n, sizeof(*reply))) == NULL) 361 return (PAM_CONV_ERR); 362 363 buffer_init(&buffer); 364 for (i = 0; i < n; ++i) { 365 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 366 case PAM_PROMPT_ECHO_OFF: 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 if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1) 373 goto fail; 374 if (buffer_get_char(&buffer) != PAM_AUTHTOK) 375 goto fail; 376 reply[i].resp = buffer_get_string(&buffer, NULL); 377 break; 378 case PAM_PROMPT_ECHO_ON: 379 buffer_put_cstring(&buffer, 380 PAM_MSG_MEMBER(msg, i, msg)); 381 if (ssh_msg_send(ctxt->pam_csock, 382 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1) 383 goto fail; 384 if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1) 385 goto fail; 386 if (buffer_get_char(&buffer) != PAM_AUTHTOK) 387 goto fail; 388 reply[i].resp = buffer_get_string(&buffer, NULL); 389 break; 390 case PAM_ERROR_MSG: 391 buffer_put_cstring(&buffer, 392 PAM_MSG_MEMBER(msg, i, msg)); 393 if (ssh_msg_send(ctxt->pam_csock, 394 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1) 395 goto fail; 396 break; 397 case PAM_TEXT_INFO: 398 buffer_put_cstring(&buffer, 399 PAM_MSG_MEMBER(msg, i, msg)); 400 if (ssh_msg_send(ctxt->pam_csock, 401 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1) 402 goto fail; 403 break; 404 default: 405 goto fail; 406 } 407 buffer_clear(&buffer); 408 } 409 buffer_free(&buffer); 410 *resp = reply; 411 return (PAM_SUCCESS); 412 413 fail: 414 for(i = 0; i < n; i++) { 415 free(reply[i].resp); 416 } 417 free(reply); 418 buffer_free(&buffer); 419 return (PAM_CONV_ERR); 420 } 421 422 /* 423 * Authentication thread. 424 */ 425 static void * 426 sshpam_thread(void *ctxtp) 427 { 428 struct pam_ctxt *ctxt = ctxtp; 429 Buffer buffer; 430 struct pam_conv sshpam_conv; 431 int flags = (options.permit_empty_passwd == 0 ? 432 PAM_DISALLOW_NULL_AUTHTOK : 0); 433 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 434 extern char **environ; 435 char **env_from_pam; 436 u_int i; 437 const char *pam_user; 438 const char **ptr_pam_user = &pam_user; 439 char *tz = getenv("TZ"); 440 441 sshpam_err = pam_get_item(sshpam_handle, PAM_USER, 442 (sshpam_const void **)ptr_pam_user); 443 if (sshpam_err != PAM_SUCCESS) 444 goto auth_fail; 445 446 environ[0] = NULL; 447 if (tz != NULL) 448 if (setenv("TZ", tz, 1) == -1) 449 error("PAM: could not set TZ environment: %s", 450 strerror(errno)); 451 452 if (sshpam_authctxt != NULL) { 453 setproctitle("%s [pam]", 454 sshpam_authctxt->valid ? pam_user : "unknown"); 455 } 456 #endif 457 458 sshpam_conv.conv = sshpam_thread_conv; 459 sshpam_conv.appdata_ptr = ctxt; 460 461 if (sshpam_authctxt == NULL) 462 fatal("%s: PAM authctxt not initialized", __func__); 463 464 buffer_init(&buffer); 465 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 466 (const void *)&sshpam_conv); 467 if (sshpam_err != PAM_SUCCESS) 468 goto auth_fail; 469 sshpam_err = pam_authenticate(sshpam_handle, flags); 470 if (sshpam_err != PAM_SUCCESS) 471 goto auth_fail; 472 473 if (compat20) { 474 if (!do_pam_account()) { 475 sshpam_err = PAM_ACCT_EXPIRED; 476 goto auth_fail; 477 } 478 if (sshpam_authctxt->force_pwchange) { 479 sshpam_err = pam_chauthtok(sshpam_handle, 480 PAM_CHANGE_EXPIRED_AUTHTOK); 481 if (sshpam_err != PAM_SUCCESS) 482 goto auth_fail; 483 sshpam_password_change_required(0); 484 } 485 } 486 487 buffer_put_cstring(&buffer, "OK"); 488 489 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 490 /* Export variables set by do_pam_account */ 491 buffer_put_int(&buffer, sshpam_account_status); 492 buffer_put_int(&buffer, sshpam_authctxt->force_pwchange); 493 494 /* Export any environment strings set in child */ 495 for(i = 0; environ[i] != NULL; i++) 496 ; /* Count */ 497 buffer_put_int(&buffer, i); 498 for(i = 0; environ[i] != NULL; i++) 499 buffer_put_cstring(&buffer, environ[i]); 500 501 /* Export any environment strings set by PAM in child */ 502 env_from_pam = pam_getenvlist(sshpam_handle); 503 for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) 504 ; /* Count */ 505 buffer_put_int(&buffer, i); 506 for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) 507 buffer_put_cstring(&buffer, env_from_pam[i]); 508 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */ 509 510 /* XXX - can't do much about an error here */ 511 ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer); 512 buffer_free(&buffer); 513 pthread_exit(NULL); 514 515 auth_fail: 516 buffer_put_cstring(&buffer, 517 pam_strerror(sshpam_handle, sshpam_err)); 518 /* XXX - can't do much about an error here */ 519 if (sshpam_err == PAM_ACCT_EXPIRED) 520 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, &buffer); 521 else 522 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer); 523 buffer_free(&buffer); 524 pthread_exit(NULL); 525 526 return (NULL); /* Avoid warning for non-pthread case */ 527 } 528 529 void 530 sshpam_thread_cleanup(void) 531 { 532 struct pam_ctxt *ctxt = cleanup_ctxt; 533 534 debug3("PAM: %s entering", __func__); 535 if (ctxt != NULL && ctxt->pam_thread != 0) { 536 pthread_cancel(ctxt->pam_thread); 537 pthread_join(ctxt->pam_thread, NULL); 538 close(ctxt->pam_psock); 539 close(ctxt->pam_csock); 540 memset(ctxt, 0, sizeof(*ctxt)); 541 cleanup_ctxt = NULL; 542 } 543 } 544 545 static int 546 sshpam_null_conv(int n, sshpam_const struct pam_message **msg, 547 struct pam_response **resp, void *data) 548 { 549 debug3("PAM: %s entering, %d messages", __func__, n); 550 return (PAM_CONV_ERR); 551 } 552 553 static struct pam_conv null_conv = { sshpam_null_conv, NULL }; 554 555 static int 556 sshpam_store_conv(int n, sshpam_const struct pam_message **msg, 557 struct pam_response **resp, void *data) 558 { 559 struct pam_response *reply; 560 int i; 561 size_t len; 562 563 debug3("PAM: %s called with %d messages", __func__, n); 564 *resp = NULL; 565 566 if (n <= 0 || n > PAM_MAX_NUM_MSG) 567 return (PAM_CONV_ERR); 568 569 if ((reply = calloc(n, sizeof(*reply))) == NULL) 570 return (PAM_CONV_ERR); 571 572 for (i = 0; i < n; ++i) { 573 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 574 case PAM_ERROR_MSG: 575 case PAM_TEXT_INFO: 576 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 577 buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len); 578 buffer_append(&loginmsg, "\n", 1 ); 579 reply[i].resp_retcode = PAM_SUCCESS; 580 break; 581 default: 582 goto fail; 583 } 584 } 585 *resp = reply; 586 return (PAM_SUCCESS); 587 588 fail: 589 for(i = 0; i < n; i++) { 590 free(reply[i].resp); 591 } 592 free(reply); 593 return (PAM_CONV_ERR); 594 } 595 596 static struct pam_conv store_conv = { sshpam_store_conv, NULL }; 597 598 void 599 sshpam_cleanup(void) 600 { 601 if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor())) 602 return; 603 debug("PAM: cleanup"); 604 pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv); 605 if (sshpam_session_open) { 606 debug("PAM: closing session"); 607 pam_close_session(sshpam_handle, PAM_SILENT); 608 sshpam_session_open = 0; 609 } 610 if (sshpam_cred_established) { 611 debug("PAM: deleting credentials"); 612 pam_setcred(sshpam_handle, PAM_DELETE_CRED); 613 sshpam_cred_established = 0; 614 } 615 sshpam_authenticated = 0; 616 pam_end(sshpam_handle, sshpam_err); 617 sshpam_handle = NULL; 618 } 619 620 static int 621 sshpam_init(Authctxt *authctxt) 622 { 623 extern char *__progname; 624 const char *pam_rhost, *pam_user, *user = authctxt->user; 625 const char **ptr_pam_user = &pam_user; 626 627 if (sshpam_handle != NULL) { 628 /* We already have a PAM context; check if the user matches */ 629 sshpam_err = pam_get_item(sshpam_handle, 630 PAM_USER, (sshpam_const void **)ptr_pam_user); 631 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0) 632 return (0); 633 pam_end(sshpam_handle, sshpam_err); 634 sshpam_handle = NULL; 635 } 636 debug("PAM: initializing for \"%s\"", user); 637 sshpam_err = 638 pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle); 639 sshpam_authctxt = authctxt; 640 641 if (sshpam_err != PAM_SUCCESS) { 642 pam_end(sshpam_handle, sshpam_err); 643 sshpam_handle = NULL; 644 return (-1); 645 } 646 pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns); 647 debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost); 648 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost); 649 if (sshpam_err != PAM_SUCCESS) { 650 pam_end(sshpam_handle, sshpam_err); 651 sshpam_handle = NULL; 652 return (-1); 653 } 654 #ifdef PAM_TTY_KLUDGE 655 /* 656 * Some silly PAM modules (e.g. pam_time) require a TTY to operate. 657 * sshd doesn't set the tty until too late in the auth process and 658 * may not even set one (for tty-less connections) 659 */ 660 debug("PAM: setting PAM_TTY to \"ssh\""); 661 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh"); 662 if (sshpam_err != PAM_SUCCESS) { 663 pam_end(sshpam_handle, sshpam_err); 664 sshpam_handle = NULL; 665 return (-1); 666 } 667 #endif 668 return (0); 669 } 670 671 static void * 672 sshpam_init_ctx(Authctxt *authctxt) 673 { 674 struct pam_ctxt *ctxt; 675 int socks[2]; 676 677 debug3("PAM: %s entering", __func__); 678 /* 679 * Refuse to start if we don't have PAM enabled or do_pam_account 680 * has previously failed. 681 */ 682 if (!options.use_pam || sshpam_account_status == 0) 683 return NULL; 684 685 /* Initialize PAM */ 686 if (sshpam_init(authctxt) == -1) { 687 error("PAM: initialization failed"); 688 return (NULL); 689 } 690 691 ctxt = xcalloc(1, sizeof *ctxt); 692 693 /* Start the authentication thread */ 694 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) { 695 error("PAM: failed create sockets: %s", strerror(errno)); 696 free(ctxt); 697 return (NULL); 698 } 699 ctxt->pam_psock = socks[0]; 700 ctxt->pam_csock = socks[1]; 701 if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) { 702 error("PAM: failed to start authentication thread: %s", 703 strerror(errno)); 704 close(socks[0]); 705 close(socks[1]); 706 free(ctxt); 707 return (NULL); 708 } 709 cleanup_ctxt = ctxt; 710 return (ctxt); 711 } 712 713 static int 714 sshpam_query(void *ctx, char **name, char **info, 715 u_int *num, char ***prompts, u_int **echo_on) 716 { 717 Buffer buffer; 718 struct pam_ctxt *ctxt = ctx; 719 size_t plen; 720 u_char type; 721 char *msg; 722 size_t len, mlen; 723 724 debug3("PAM: %s entering", __func__); 725 buffer_init(&buffer); 726 *name = xstrdup(""); 727 *info = xstrdup(""); 728 *prompts = xmalloc(sizeof(char *)); 729 **prompts = NULL; 730 plen = 0; 731 *echo_on = xmalloc(sizeof(u_int)); 732 while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) { 733 type = buffer_get_char(&buffer); 734 msg = buffer_get_string(&buffer, NULL); 735 mlen = strlen(msg); 736 switch (type) { 737 case PAM_PROMPT_ECHO_ON: 738 case PAM_PROMPT_ECHO_OFF: 739 *num = 1; 740 len = plen + mlen + 1; 741 **prompts = xreallocarray(**prompts, 1, len); 742 strlcpy(**prompts + plen, msg, len - plen); 743 plen += mlen; 744 **echo_on = (type == PAM_PROMPT_ECHO_ON); 745 free(msg); 746 return (0); 747 case PAM_ERROR_MSG: 748 case PAM_TEXT_INFO: 749 /* accumulate messages */ 750 len = plen + mlen + 2; 751 **prompts = xreallocarray(**prompts, 1, len); 752 strlcpy(**prompts + plen, msg, len - plen); 753 plen += mlen; 754 strlcat(**prompts + plen, "\n", len - plen); 755 plen++; 756 free(msg); 757 break; 758 case PAM_ACCT_EXPIRED: 759 sshpam_account_status = 0; 760 /* FALLTHROUGH */ 761 case PAM_AUTH_ERR: 762 debug3("PAM: %s", pam_strerror(sshpam_handle, type)); 763 if (**prompts != NULL && strlen(**prompts) != 0) { 764 *info = **prompts; 765 **prompts = NULL; 766 *num = 0; 767 **echo_on = 0; 768 ctxt->pam_done = -1; 769 free(msg); 770 return 0; 771 } 772 /* FALLTHROUGH */ 773 case PAM_SUCCESS: 774 if (**prompts != NULL) { 775 /* drain any accumulated messages */ 776 debug("PAM: %s", **prompts); 777 buffer_append(&loginmsg, **prompts, 778 strlen(**prompts)); 779 free(**prompts); 780 **prompts = NULL; 781 } 782 if (type == PAM_SUCCESS) { 783 if (!sshpam_authctxt->valid || 784 (sshpam_authctxt->pw->pw_uid == 0 && 785 options.permit_root_login != PERMIT_YES)) 786 fatal("Internal error: PAM auth " 787 "succeeded when it should have " 788 "failed"); 789 import_environments(&buffer); 790 *num = 0; 791 **echo_on = 0; 792 ctxt->pam_done = 1; 793 free(msg); 794 return (0); 795 } 796 error("PAM: %s for %s%.100s from %.100s", msg, 797 sshpam_authctxt->valid ? "" : "illegal user ", 798 sshpam_authctxt->user, 799 get_remote_name_or_ip(utmp_len, options.use_dns)); 800 /* FALLTHROUGH */ 801 default: 802 *num = 0; 803 **echo_on = 0; 804 free(msg); 805 ctxt->pam_done = -1; 806 return (-1); 807 } 808 } 809 return (-1); 810 } 811 812 /* XXX - see also comment in auth-chall.c:verify_response */ 813 static int 814 sshpam_respond(void *ctx, u_int num, char **resp) 815 { 816 Buffer buffer; 817 struct pam_ctxt *ctxt = ctx; 818 819 debug2("PAM: %s entering, %u responses", __func__, num); 820 switch (ctxt->pam_done) { 821 case 1: 822 sshpam_authenticated = 1; 823 return (0); 824 case 0: 825 break; 826 default: 827 return (-1); 828 } 829 if (num != 1) { 830 error("PAM: expected one response, got %u", num); 831 return (-1); 832 } 833 buffer_init(&buffer); 834 if (sshpam_authctxt->valid && 835 (sshpam_authctxt->pw->pw_uid != 0 || 836 options.permit_root_login == PERMIT_YES)) 837 buffer_put_cstring(&buffer, *resp); 838 else 839 buffer_put_cstring(&buffer, badpw); 840 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) { 841 buffer_free(&buffer); 842 return (-1); 843 } 844 buffer_free(&buffer); 845 return (1); 846 } 847 848 static void 849 sshpam_free_ctx(void *ctxtp) 850 { 851 struct pam_ctxt *ctxt = ctxtp; 852 853 debug3("PAM: %s entering", __func__); 854 sshpam_thread_cleanup(); 855 free(ctxt); 856 /* 857 * We don't call sshpam_cleanup() here because we may need the PAM 858 * handle at a later stage, e.g. when setting up a session. It's 859 * still on the cleanup list, so pam_end() *will* be called before 860 * the server process terminates. 861 */ 862 } 863 864 KbdintDevice sshpam_device = { 865 "pam", 866 sshpam_init_ctx, 867 sshpam_query, 868 sshpam_respond, 869 sshpam_free_ctx 870 }; 871 872 KbdintDevice mm_sshpam_device = { 873 "pam", 874 mm_sshpam_init_ctx, 875 mm_sshpam_query, 876 mm_sshpam_respond, 877 mm_sshpam_free_ctx 878 }; 879 880 /* 881 * This replaces auth-pam.c 882 */ 883 void 884 start_pam(Authctxt *authctxt) 885 { 886 if (!options.use_pam) 887 fatal("PAM: initialisation requested when UsePAM=no"); 888 889 if (sshpam_init(authctxt) == -1) 890 fatal("PAM: initialisation failed"); 891 } 892 893 void 894 finish_pam(void) 895 { 896 sshpam_cleanup(); 897 } 898 899 u_int 900 do_pam_account(void) 901 { 902 debug("%s: called", __func__); 903 if (sshpam_account_status != -1) 904 return (sshpam_account_status); 905 906 sshpam_err = pam_acct_mgmt(sshpam_handle, 0); 907 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err, 908 pam_strerror(sshpam_handle, sshpam_err)); 909 910 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) { 911 sshpam_account_status = 0; 912 return (sshpam_account_status); 913 } 914 915 if (sshpam_err == PAM_NEW_AUTHTOK_REQD) 916 sshpam_password_change_required(1); 917 918 sshpam_account_status = 1; 919 return (sshpam_account_status); 920 } 921 922 void 923 do_pam_set_tty(const char *tty) 924 { 925 if (tty != NULL) { 926 debug("PAM: setting PAM_TTY to \"%s\"", tty); 927 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty); 928 if (sshpam_err != PAM_SUCCESS) 929 fatal("PAM: failed to set PAM_TTY: %s", 930 pam_strerror(sshpam_handle, sshpam_err)); 931 } 932 } 933 934 void 935 do_pam_setcred(int init) 936 { 937 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 938 (const void *)&store_conv); 939 if (sshpam_err != PAM_SUCCESS) 940 fatal("PAM: failed to set PAM_CONV: %s", 941 pam_strerror(sshpam_handle, sshpam_err)); 942 if (init) { 943 debug("PAM: establishing credentials"); 944 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED); 945 } else { 946 debug("PAM: reinitializing credentials"); 947 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED); 948 } 949 if (sshpam_err == PAM_SUCCESS) { 950 sshpam_cred_established = 1; 951 return; 952 } 953 if (sshpam_authenticated) 954 fatal("PAM: pam_setcred(): %s", 955 pam_strerror(sshpam_handle, sshpam_err)); 956 else 957 debug("PAM: pam_setcred(): %s", 958 pam_strerror(sshpam_handle, sshpam_err)); 959 } 960 961 static int 962 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg, 963 struct pam_response **resp, void *data) 964 { 965 char input[PAM_MAX_MSG_SIZE]; 966 struct pam_response *reply; 967 int i; 968 969 debug3("PAM: %s called with %d messages", __func__, n); 970 971 *resp = NULL; 972 973 if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO)) 974 return (PAM_CONV_ERR); 975 976 if ((reply = calloc(n, sizeof(*reply))) == NULL) 977 return (PAM_CONV_ERR); 978 979 for (i = 0; i < n; ++i) { 980 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 981 case PAM_PROMPT_ECHO_OFF: 982 reply[i].resp = 983 read_passphrase(PAM_MSG_MEMBER(msg, i, msg), 984 RP_ALLOW_STDIN); 985 reply[i].resp_retcode = PAM_SUCCESS; 986 break; 987 case PAM_PROMPT_ECHO_ON: 988 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 989 if (fgets(input, sizeof input, stdin) == NULL) 990 input[0] = '\0'; 991 if ((reply[i].resp = strdup(input)) == NULL) 992 goto fail; 993 reply[i].resp_retcode = PAM_SUCCESS; 994 break; 995 case PAM_ERROR_MSG: 996 case PAM_TEXT_INFO: 997 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 998 reply[i].resp_retcode = PAM_SUCCESS; 999 break; 1000 default: 1001 goto fail; 1002 } 1003 } 1004 *resp = reply; 1005 return (PAM_SUCCESS); 1006 1007 fail: 1008 for(i = 0; i < n; i++) { 1009 free(reply[i].resp); 1010 } 1011 free(reply); 1012 return (PAM_CONV_ERR); 1013 } 1014 1015 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL }; 1016 1017 /* 1018 * XXX this should be done in the authentication phase, but ssh1 doesn't 1019 * support that 1020 */ 1021 void 1022 do_pam_chauthtok(void) 1023 { 1024 if (use_privsep) 1025 fatal("Password expired (unable to change with privsep)"); 1026 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1027 (const void *)&tty_conv); 1028 if (sshpam_err != PAM_SUCCESS) 1029 fatal("PAM: failed to set PAM_CONV: %s", 1030 pam_strerror(sshpam_handle, sshpam_err)); 1031 debug("PAM: changing password"); 1032 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK); 1033 if (sshpam_err != PAM_SUCCESS) 1034 fatal("PAM: pam_chauthtok(): %s", 1035 pam_strerror(sshpam_handle, sshpam_err)); 1036 } 1037 1038 void 1039 do_pam_session(void) 1040 { 1041 debug3("PAM: opening session"); 1042 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1043 (const void *)&store_conv); 1044 if (sshpam_err != PAM_SUCCESS) 1045 fatal("PAM: failed to set PAM_CONV: %s", 1046 pam_strerror(sshpam_handle, sshpam_err)); 1047 sshpam_err = pam_open_session(sshpam_handle, 0); 1048 if (sshpam_err == PAM_SUCCESS) 1049 sshpam_session_open = 1; 1050 else { 1051 sshpam_session_open = 0; 1052 disable_forwarding(); 1053 error("PAM: pam_open_session(): %s", 1054 pam_strerror(sshpam_handle, sshpam_err)); 1055 } 1056 1057 } 1058 1059 int 1060 is_pam_session_open(void) 1061 { 1062 return sshpam_session_open; 1063 } 1064 1065 /* 1066 * Set a PAM environment string. We need to do this so that the session 1067 * modules can handle things like Kerberos/GSI credentials that appear 1068 * during the ssh authentication process. 1069 */ 1070 int 1071 do_pam_putenv(char *name, char *value) 1072 { 1073 int ret = 1; 1074 #ifdef HAVE_PAM_PUTENV 1075 char *compound; 1076 size_t len; 1077 1078 len = strlen(name) + strlen(value) + 2; 1079 compound = xmalloc(len); 1080 1081 snprintf(compound, len, "%s=%s", name, value); 1082 ret = pam_putenv(sshpam_handle, compound); 1083 free(compound); 1084 #endif 1085 1086 return (ret); 1087 } 1088 1089 char ** 1090 fetch_pam_child_environment(void) 1091 { 1092 return sshpam_env; 1093 } 1094 1095 char ** 1096 fetch_pam_environment(void) 1097 { 1098 return (pam_getenvlist(sshpam_handle)); 1099 } 1100 1101 void 1102 free_pam_environment(char **env) 1103 { 1104 char **envp; 1105 1106 if (env == NULL) 1107 return; 1108 1109 for (envp = env; *envp; envp++) 1110 free(*envp); 1111 free(env); 1112 } 1113 1114 /* 1115 * "Blind" conversation function for password authentication. Assumes that 1116 * echo-off prompts are for the password and stores messages for later 1117 * display. 1118 */ 1119 static int 1120 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg, 1121 struct pam_response **resp, void *data) 1122 { 1123 struct pam_response *reply; 1124 int i; 1125 size_t len; 1126 1127 debug3("PAM: %s called with %d messages", __func__, n); 1128 1129 *resp = NULL; 1130 1131 if (n <= 0 || n > PAM_MAX_NUM_MSG) 1132 return (PAM_CONV_ERR); 1133 1134 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1135 return (PAM_CONV_ERR); 1136 1137 for (i = 0; i < n; ++i) { 1138 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1139 case PAM_PROMPT_ECHO_OFF: 1140 if (sshpam_password == NULL) 1141 goto fail; 1142 if ((reply[i].resp = strdup(sshpam_password)) == NULL) 1143 goto fail; 1144 reply[i].resp_retcode = PAM_SUCCESS; 1145 break; 1146 case PAM_ERROR_MSG: 1147 case PAM_TEXT_INFO: 1148 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 1149 if (len > 0) { 1150 buffer_append(&loginmsg, 1151 PAM_MSG_MEMBER(msg, i, msg), len); 1152 buffer_append(&loginmsg, "\n", 1); 1153 } 1154 if ((reply[i].resp = strdup("")) == NULL) 1155 goto fail; 1156 reply[i].resp_retcode = PAM_SUCCESS; 1157 break; 1158 default: 1159 goto fail; 1160 } 1161 } 1162 *resp = reply; 1163 return (PAM_SUCCESS); 1164 1165 fail: 1166 for(i = 0; i < n; i++) { 1167 free(reply[i].resp); 1168 } 1169 free(reply); 1170 return (PAM_CONV_ERR); 1171 } 1172 1173 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL }; 1174 1175 /* 1176 * Attempt password authentication via PAM 1177 */ 1178 int 1179 sshpam_auth_passwd(Authctxt *authctxt, const char *password) 1180 { 1181 int flags = (options.permit_empty_passwd == 0 ? 1182 PAM_DISALLOW_NULL_AUTHTOK : 0); 1183 1184 if (!options.use_pam || sshpam_handle == NULL) 1185 fatal("PAM: %s called when PAM disabled or failed to " 1186 "initialise.", __func__); 1187 1188 sshpam_password = password; 1189 sshpam_authctxt = authctxt; 1190 1191 /* 1192 * If the user logging in is invalid, or is root but is not permitted 1193 * by PermitRootLogin, use an invalid password to prevent leaking 1194 * information via timing (eg if the PAM config has a delay on fail). 1195 */ 1196 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 && 1197 options.permit_root_login != PERMIT_YES)) 1198 sshpam_password = badpw; 1199 1200 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1201 (const void *)&passwd_conv); 1202 if (sshpam_err != PAM_SUCCESS) 1203 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__, 1204 pam_strerror(sshpam_handle, sshpam_err)); 1205 1206 sshpam_err = pam_authenticate(sshpam_handle, flags); 1207 sshpam_password = NULL; 1208 if (sshpam_err == PAM_SUCCESS && authctxt->valid) { 1209 debug("PAM: password authentication accepted for %.100s", 1210 authctxt->user); 1211 return 1; 1212 } else { 1213 debug("PAM: password authentication failed for %.100s: %s", 1214 authctxt->valid ? authctxt->user : "an illegal user", 1215 pam_strerror(sshpam_handle, sshpam_err)); 1216 return 0; 1217 } 1218 } 1219 #endif /* USE_PAM */ 1220
