auth-pam.c revision 318402
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 FreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des */ 49 50#include "includes.h" 51 52#include <sys/types.h> 53#include <sys/stat.h> 54#include <sys/wait.h> 55 56#include <errno.h> 57#include <signal.h> 58#include <stdarg.h> 59#include <string.h> 60#include <unistd.h> 61 62#ifdef USE_PAM 63#if defined(HAVE_SECURITY_PAM_APPL_H) 64#include <security/pam_appl.h> 65#elif defined (HAVE_PAM_PAM_APPL_H) 66#include <pam/pam_appl.h> 67#endif 68 69/* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */ 70#ifdef PAM_SUN_CODEBASE 71# define sshpam_const /* Solaris, HP-UX, AIX */ 72#else 73# define sshpam_const const /* LinuxPAM, OpenPAM */ 74#endif 75 76/* Ambiguity in spec: is it an array of pointers or a pointer to an array? */ 77#ifdef PAM_SUN_CODEBASE 78# define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member) 79#else 80# define PAM_MSG_MEMBER(msg, n, member) ((msg)[(n)]->member) 81#endif 82 83#include "xmalloc.h" 84#include "buffer.h" 85#include "key.h" 86#include "hostfile.h" 87#include "auth.h" 88#include "auth-pam.h" 89#include "canohost.h" 90#include "log.h" 91#include "msg.h" 92#include "packet.h" 93#include "misc.h" 94#include "servconf.h" 95#include "ssh2.h" 96#include "auth-options.h" 97#ifdef GSSAPI 98#include "ssh-gss.h" 99#endif 100#include "monitor_wrap.h" 101#include "blacklist_client.h" 102 103extern ServerOptions options; 104extern Buffer loginmsg; 105extern int compat20; 106extern u_int utmp_len; 107 108/* so we don't silently change behaviour */ 109#ifdef USE_POSIX_THREADS 110# error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK" 111#endif 112 113/* 114 * Formerly known as USE_POSIX_THREADS, using this is completely unsupported 115 * and generally a bad idea. Use at own risk and do not expect support if 116 * this breaks. 117 */ 118#ifdef UNSUPPORTED_POSIX_THREADS_HACK 119#include <pthread.h> 120/* 121 * Avoid namespace clash when *not* using pthreads for systems *with* 122 * pthreads, which unconditionally define pthread_t via sys/types.h 123 * (e.g. Linux) 124 */ 125typedef pthread_t sp_pthread_t; 126#else 127typedef pid_t sp_pthread_t; 128#endif 129 130struct pam_ctxt { 131 sp_pthread_t pam_thread; 132 int pam_psock; 133 int pam_csock; 134 int pam_done; 135}; 136 137static void sshpam_free_ctx(void *); 138static struct pam_ctxt *cleanup_ctxt; 139 140#ifndef UNSUPPORTED_POSIX_THREADS_HACK 141/* 142 * Simulate threads with processes. 143 */ 144 145static int sshpam_thread_status = -1; 146static mysig_t sshpam_oldsig; 147 148static void 149sshpam_sigchld_handler(int sig) 150{ 151 signal(SIGCHLD, SIG_DFL); 152 if (cleanup_ctxt == NULL) 153 return; /* handler called after PAM cleanup, shouldn't happen */ 154 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG) 155 <= 0) { 156 /* PAM thread has not exitted, privsep slave must have */ 157 kill(cleanup_ctxt->pam_thread, SIGTERM); 158 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, 0) 159 <= 0) 160 return; /* could not wait */ 161 } 162 if (WIFSIGNALED(sshpam_thread_status) && 163 WTERMSIG(sshpam_thread_status) == SIGTERM) 164 return; /* terminated by pthread_cancel */ 165 if (!WIFEXITED(sshpam_thread_status)) 166 sigdie("PAM: authentication thread exited unexpectedly"); 167 if (WEXITSTATUS(sshpam_thread_status) != 0) 168 sigdie("PAM: authentication thread exited uncleanly"); 169} 170 171/* ARGSUSED */ 172static void 173pthread_exit(void *value) 174{ 175 _exit(0); 176} 177 178/* ARGSUSED */ 179static int 180pthread_create(sp_pthread_t *thread, const void *attr, 181 void *(*thread_start)(void *), void *arg) 182{ 183 pid_t pid; 184 struct pam_ctxt *ctx = arg; 185 186 sshpam_thread_status = -1; 187 switch ((pid = fork())) { 188 case -1: 189 error("fork(): %s", strerror(errno)); 190 return (-1); 191 case 0: 192 close(ctx->pam_psock); 193 ctx->pam_psock = -1; 194 thread_start(arg); 195 _exit(1); 196 default: 197 *thread = pid; 198 close(ctx->pam_csock); 199 ctx->pam_csock = -1; 200 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler); 201 return (0); 202 } 203} 204 205static int 206pthread_cancel(sp_pthread_t thread) 207{ 208 signal(SIGCHLD, sshpam_oldsig); 209 return (kill(thread, SIGTERM)); 210} 211 212/* ARGSUSED */ 213static int 214pthread_join(sp_pthread_t thread, void **value) 215{ 216 int status; 217 218 if (sshpam_thread_status != -1) 219 return (sshpam_thread_status); 220 signal(SIGCHLD, sshpam_oldsig); 221 waitpid(thread, &status, 0); 222 return (status); 223} 224#endif 225 226 227static pam_handle_t *sshpam_handle = NULL; 228static int sshpam_err = 0; 229static int sshpam_authenticated = 0; 230static int sshpam_session_open = 0; 231static int sshpam_cred_established = 0; 232static int sshpam_account_status = -1; 233static char **sshpam_env = NULL; 234static Authctxt *sshpam_authctxt = NULL; 235static const char *sshpam_password = NULL; 236static char badpw[] = "\b\n\r\177INCORRECT"; 237 238/* Some PAM implementations don't implement this */ 239#ifndef HAVE_PAM_GETENVLIST 240static char ** 241pam_getenvlist(pam_handle_t *pamh) 242{ 243 /* 244 * XXX - If necessary, we can still support envrionment passing 245 * for platforms without pam_getenvlist by searching for known 246 * env vars (e.g. KRB5CCNAME) from the PAM environment. 247 */ 248 return NULL; 249} 250#endif 251 252/* 253 * Some platforms, notably Solaris, do not enforce password complexity 254 * rules during pam_chauthtok() if the real uid of the calling process 255 * is 0, on the assumption that it's being called by "passwd" run by root. 256 * This wraps pam_chauthtok and sets/restore the real uid so PAM will do 257 * the right thing. 258 */ 259#ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID 260static int 261sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags) 262{ 263 int result; 264 265 if (sshpam_authctxt == NULL) 266 fatal("PAM: sshpam_authctxt not initialized"); 267 if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1) 268 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 269 result = pam_chauthtok(pamh, flags); 270 if (setreuid(0, -1) == -1) 271 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 272 return result; 273} 274# define pam_chauthtok(a,b) (sshpam_chauthtok_ruid((a), (b))) 275#endif 276 277void 278sshpam_password_change_required(int reqd) 279{ 280 debug3("%s %d", __func__, reqd); 281 if (sshpam_authctxt == NULL) 282 fatal("%s: PAM authctxt not initialized", __func__); 283 sshpam_authctxt->force_pwchange = reqd; 284 if (reqd) { 285 no_port_forwarding_flag |= 2; 286 no_agent_forwarding_flag |= 2; 287 no_x11_forwarding_flag |= 2; 288 } else { 289 no_port_forwarding_flag &= ~2; 290 no_agent_forwarding_flag &= ~2; 291 no_x11_forwarding_flag &= ~2; 292 } 293} 294 295/* Import regular and PAM environment from subprocess */ 296static void 297import_environments(Buffer *b) 298{ 299 char *env; 300 u_int i, num_env; 301 int err; 302 303 debug3("PAM: %s entering", __func__); 304 305#ifndef UNSUPPORTED_POSIX_THREADS_HACK 306 /* Import variables set by do_pam_account */ 307 sshpam_account_status = buffer_get_int(b); 308 sshpam_password_change_required(buffer_get_int(b)); 309 310 /* Import environment from subprocess */ 311 num_env = buffer_get_int(b); 312 if (num_env > 1024) 313 fatal("%s: received %u environment variables, expected <= 1024", 314 __func__, num_env); 315 sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env)); 316 debug3("PAM: num env strings %d", num_env); 317 for(i = 0; i < num_env; i++) 318 sshpam_env[i] = buffer_get_string(b, NULL); 319 320 sshpam_env[num_env] = NULL; 321 322 /* Import PAM environment from subprocess */ 323 num_env = buffer_get_int(b); 324 debug("PAM: num PAM env strings %d", num_env); 325 for(i = 0; i < num_env; i++) { 326 env = buffer_get_string(b, NULL); 327 328#ifdef HAVE_PAM_PUTENV 329 /* Errors are not fatal here */ 330 if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) { 331 error("PAM: pam_putenv: %s", 332 pam_strerror(sshpam_handle, sshpam_err)); 333 } 334#endif 335 } 336#endif 337} 338 339/* 340 * Conversation function for authentication thread. 341 */ 342static int 343sshpam_thread_conv(int n, sshpam_const struct pam_message **msg, 344 struct pam_response **resp, void *data) 345{ 346 Buffer buffer; 347 struct pam_ctxt *ctxt; 348 struct pam_response *reply; 349 int i; 350 351 debug3("PAM: %s entering, %d messages", __func__, n); 352 *resp = NULL; 353 354 if (data == NULL) { 355 error("PAM: conversation function passed a null context"); 356 return (PAM_CONV_ERR); 357 } 358 ctxt = data; 359 if (n <= 0 || n > PAM_MAX_NUM_MSG) 360 return (PAM_CONV_ERR); 361 362 if ((reply = calloc(n, sizeof(*reply))) == NULL) 363 return (PAM_CONV_ERR); 364 365 buffer_init(&buffer); 366 for (i = 0; i < n; ++i) { 367 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 368 case PAM_PROMPT_ECHO_OFF: 369 buffer_put_cstring(&buffer, 370 PAM_MSG_MEMBER(msg, i, msg)); 371 if (ssh_msg_send(ctxt->pam_csock, 372 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1) 373 goto fail; 374 if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1) 375 goto fail; 376 if (buffer_get_char(&buffer) != PAM_AUTHTOK) 377 goto fail; 378 reply[i].resp = buffer_get_string(&buffer, NULL); 379 break; 380 case PAM_PROMPT_ECHO_ON: 381 buffer_put_cstring(&buffer, 382 PAM_MSG_MEMBER(msg, i, msg)); 383 if (ssh_msg_send(ctxt->pam_csock, 384 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1) 385 goto fail; 386 if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1) 387 goto fail; 388 if (buffer_get_char(&buffer) != PAM_AUTHTOK) 389 goto fail; 390 reply[i].resp = buffer_get_string(&buffer, NULL); 391 break; 392 case PAM_ERROR_MSG: 393 buffer_put_cstring(&buffer, 394 PAM_MSG_MEMBER(msg, i, msg)); 395 if (ssh_msg_send(ctxt->pam_csock, 396 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1) 397 goto fail; 398 break; 399 case PAM_TEXT_INFO: 400 buffer_put_cstring(&buffer, 401 PAM_MSG_MEMBER(msg, i, msg)); 402 if (ssh_msg_send(ctxt->pam_csock, 403 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1) 404 goto fail; 405 break; 406 default: 407 goto fail; 408 } 409 buffer_clear(&buffer); 410 } 411 buffer_free(&buffer); 412 *resp = reply; 413 return (PAM_SUCCESS); 414 415 fail: 416 for(i = 0; i < n; i++) { 417 free(reply[i].resp); 418 } 419 free(reply); 420 buffer_free(&buffer); 421 return (PAM_CONV_ERR); 422} 423 424/* 425 * Authentication thread. 426 */ 427static void * 428sshpam_thread(void *ctxtp) 429{ 430 struct pam_ctxt *ctxt = ctxtp; 431 Buffer buffer; 432 struct pam_conv sshpam_conv; 433 int flags = (options.permit_empty_passwd == 0 ? 434 PAM_DISALLOW_NULL_AUTHTOK : 0); 435#ifndef UNSUPPORTED_POSIX_THREADS_HACK 436 extern char **environ; 437 char **env_from_pam; 438 u_int i; 439 const char *pam_user; 440 const char **ptr_pam_user = &pam_user; 441 char *tz = getenv("TZ"); 442 443 sshpam_err = pam_get_item(sshpam_handle, PAM_USER, 444 (sshpam_const void **)ptr_pam_user); 445 if (sshpam_err != PAM_SUCCESS) 446 goto auth_fail; 447 448 environ[0] = NULL; 449 if (tz != NULL) 450 if (setenv("TZ", tz, 1) == -1) 451 error("PAM: could not set TZ environment: %s", 452 strerror(errno)); 453 454 if (sshpam_authctxt != NULL) { 455 setproctitle("%s [pam]", 456 sshpam_authctxt->valid ? pam_user : "unknown"); 457 } 458#endif 459 460 sshpam_conv.conv = sshpam_thread_conv; 461 sshpam_conv.appdata_ptr = ctxt; 462 463 if (sshpam_authctxt == NULL) 464 fatal("%s: PAM authctxt not initialized", __func__); 465 466 buffer_init(&buffer); 467 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 468 (const void *)&sshpam_conv); 469 if (sshpam_err != PAM_SUCCESS) 470 goto auth_fail; 471 sshpam_err = pam_authenticate(sshpam_handle, flags); 472 if (sshpam_err != PAM_SUCCESS) 473 goto auth_fail; 474 475 if (compat20) { 476 if (!do_pam_account()) { 477 sshpam_err = PAM_ACCT_EXPIRED; 478 goto auth_fail; 479 } 480 if (sshpam_authctxt->force_pwchange) { 481 sshpam_err = pam_chauthtok(sshpam_handle, 482 PAM_CHANGE_EXPIRED_AUTHTOK); 483 if (sshpam_err != PAM_SUCCESS) 484 goto auth_fail; 485 sshpam_password_change_required(0); 486 } 487 } 488 489 buffer_put_cstring(&buffer, "OK"); 490 491#ifndef UNSUPPORTED_POSIX_THREADS_HACK 492 /* Export variables set by do_pam_account */ 493 buffer_put_int(&buffer, sshpam_account_status); 494 buffer_put_int(&buffer, sshpam_authctxt->force_pwchange); 495 496 /* Export any environment strings set in child */ 497 for(i = 0; environ[i] != NULL; i++) 498 ; /* Count */ 499 buffer_put_int(&buffer, i); 500 for(i = 0; environ[i] != NULL; i++) 501 buffer_put_cstring(&buffer, environ[i]); 502 503 /* Export any environment strings set by PAM in child */ 504 env_from_pam = pam_getenvlist(sshpam_handle); 505 for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) 506 ; /* Count */ 507 buffer_put_int(&buffer, i); 508 for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) 509 buffer_put_cstring(&buffer, env_from_pam[i]); 510#endif /* UNSUPPORTED_POSIX_THREADS_HACK */ 511 512 /* XXX - can't do much about an error here */ 513 ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer); 514 buffer_free(&buffer); 515 pthread_exit(NULL); 516 517 auth_fail: 518 buffer_put_cstring(&buffer, 519 pam_strerror(sshpam_handle, sshpam_err)); 520 /* XXX - can't do much about an error here */ 521 if (sshpam_err == PAM_ACCT_EXPIRED) 522 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, &buffer); 523 else 524 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer); 525 buffer_free(&buffer); 526 pthread_exit(NULL); 527 528 return (NULL); /* Avoid warning for non-pthread case */ 529} 530 531void 532sshpam_thread_cleanup(void) 533{ 534 struct pam_ctxt *ctxt = cleanup_ctxt; 535 536 debug3("PAM: %s entering", __func__); 537 if (ctxt != NULL && ctxt->pam_thread != 0) { 538 pthread_cancel(ctxt->pam_thread); 539 pthread_join(ctxt->pam_thread, NULL); 540 close(ctxt->pam_psock); 541 close(ctxt->pam_csock); 542 memset(ctxt, 0, sizeof(*ctxt)); 543 cleanup_ctxt = NULL; 544 } 545} 546 547static int 548sshpam_null_conv(int n, sshpam_const struct pam_message **msg, 549 struct pam_response **resp, void *data) 550{ 551 debug3("PAM: %s entering, %d messages", __func__, n); 552 return (PAM_CONV_ERR); 553} 554 555static struct pam_conv null_conv = { sshpam_null_conv, NULL }; 556 557static int 558sshpam_store_conv(int n, sshpam_const struct pam_message **msg, 559 struct pam_response **resp, void *data) 560{ 561 struct pam_response *reply; 562 int i; 563 size_t len; 564 565 debug3("PAM: %s called with %d messages", __func__, n); 566 *resp = NULL; 567 568 if (n <= 0 || n > PAM_MAX_NUM_MSG) 569 return (PAM_CONV_ERR); 570 571 if ((reply = calloc(n, sizeof(*reply))) == NULL) 572 return (PAM_CONV_ERR); 573 574 for (i = 0; i < n; ++i) { 575 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 576 case PAM_ERROR_MSG: 577 case PAM_TEXT_INFO: 578 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 579 buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len); 580 buffer_append(&loginmsg, "\n", 1 ); 581 reply[i].resp_retcode = PAM_SUCCESS; 582 break; 583 default: 584 goto fail; 585 } 586 } 587 *resp = reply; 588 return (PAM_SUCCESS); 589 590 fail: 591 for(i = 0; i < n; i++) { 592 free(reply[i].resp); 593 } 594 free(reply); 595 return (PAM_CONV_ERR); 596} 597 598static struct pam_conv store_conv = { sshpam_store_conv, NULL }; 599 600void 601sshpam_cleanup(void) 602{ 603 if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor())) 604 return; 605 debug("PAM: cleanup"); 606 pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv); 607 if (sshpam_session_open) { 608 debug("PAM: closing session"); 609 pam_close_session(sshpam_handle, PAM_SILENT); 610 sshpam_session_open = 0; 611 } 612 if (sshpam_cred_established) { 613 debug("PAM: deleting credentials"); 614 pam_setcred(sshpam_handle, PAM_DELETE_CRED); 615 sshpam_cred_established = 0; 616 } 617 sshpam_authenticated = 0; 618 pam_end(sshpam_handle, sshpam_err); 619 sshpam_handle = NULL; 620} 621 622static int 623sshpam_init(Authctxt *authctxt) 624{ 625 extern char *__progname; 626 const char *pam_rhost, *pam_user, *user = authctxt->user; 627 const char **ptr_pam_user = &pam_user; 628 629 if (sshpam_handle != NULL) { 630 /* We already have a PAM context; check if the user matches */ 631 sshpam_err = pam_get_item(sshpam_handle, 632 PAM_USER, (sshpam_const void **)ptr_pam_user); 633 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0) 634 return (0); 635 pam_end(sshpam_handle, sshpam_err); 636 sshpam_handle = NULL; 637 } 638 debug("PAM: initializing for \"%s\"", user); 639 sshpam_err = 640 pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle); 641 sshpam_authctxt = authctxt; 642 643 if (sshpam_err != PAM_SUCCESS) { 644 pam_end(sshpam_handle, sshpam_err); 645 sshpam_handle = NULL; 646 return (-1); 647 } 648 pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns); 649 debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost); 650 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost); 651 if (sshpam_err != PAM_SUCCESS) { 652 pam_end(sshpam_handle, sshpam_err); 653 sshpam_handle = NULL; 654 return (-1); 655 } 656#ifdef PAM_TTY_KLUDGE 657 /* 658 * Some silly PAM modules (e.g. pam_time) require a TTY to operate. 659 * sshd doesn't set the tty until too late in the auth process and 660 * may not even set one (for tty-less connections) 661 */ 662 debug("PAM: setting PAM_TTY to \"ssh\""); 663 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh"); 664 if (sshpam_err != PAM_SUCCESS) { 665 pam_end(sshpam_handle, sshpam_err); 666 sshpam_handle = NULL; 667 return (-1); 668 } 669#endif 670 return (0); 671} 672 673static void * 674sshpam_init_ctx(Authctxt *authctxt) 675{ 676 struct pam_ctxt *ctxt; 677 int socks[2]; 678 679 debug3("PAM: %s entering", __func__); 680 /* 681 * Refuse to start if we don't have PAM enabled or do_pam_account 682 * has previously failed. 683 */ 684 if (!options.use_pam || sshpam_account_status == 0) 685 return NULL; 686 687 /* Initialize PAM */ 688 if (sshpam_init(authctxt) == -1) { 689 error("PAM: initialization failed"); 690 return (NULL); 691 } 692 693 ctxt = xcalloc(1, sizeof *ctxt); 694 695 /* Start the authentication thread */ 696 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) { 697 error("PAM: failed create sockets: %s", strerror(errno)); 698 free(ctxt); 699 return (NULL); 700 } 701 ctxt->pam_psock = socks[0]; 702 ctxt->pam_csock = socks[1]; 703 if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) { 704 error("PAM: failed to start authentication thread: %s", 705 strerror(errno)); 706 close(socks[0]); 707 close(socks[1]); 708 free(ctxt); 709 return (NULL); 710 } 711 cleanup_ctxt = ctxt; 712 return (ctxt); 713} 714 715static int 716sshpam_query(void *ctx, char **name, char **info, 717 u_int *num, char ***prompts, u_int **echo_on) 718{ 719 Buffer buffer; 720 struct pam_ctxt *ctxt = ctx; 721 size_t plen; 722 u_char type; 723 char *msg; 724 size_t len, mlen; 725 726 debug3("PAM: %s entering", __func__); 727 buffer_init(&buffer); 728 *name = xstrdup(""); 729 *info = xstrdup(""); 730 *prompts = xmalloc(sizeof(char *)); 731 **prompts = NULL; 732 plen = 0; 733 *echo_on = xmalloc(sizeof(u_int)); 734 while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) { 735 type = buffer_get_char(&buffer); 736 msg = buffer_get_string(&buffer, NULL); 737 mlen = strlen(msg); 738 switch (type) { 739 case PAM_PROMPT_ECHO_ON: 740 case PAM_PROMPT_ECHO_OFF: 741 *num = 1; 742 len = plen + mlen + 1; 743 **prompts = xreallocarray(**prompts, 1, len); 744 strlcpy(**prompts + plen, msg, len - plen); 745 plen += mlen; 746 **echo_on = (type == PAM_PROMPT_ECHO_ON); 747 free(msg); 748 return (0); 749 case PAM_ERROR_MSG: 750 case PAM_TEXT_INFO: 751 /* accumulate messages */ 752 len = plen + mlen + 2; 753 **prompts = xreallocarray(**prompts, 1, len); 754 strlcpy(**prompts + plen, msg, len - plen); 755 plen += mlen; 756 strlcat(**prompts + plen, "\n", len - plen); 757 plen++; 758 free(msg); 759 break; 760 case PAM_ACCT_EXPIRED: 761 sshpam_account_status = 0; 762 /* FALLTHROUGH */ 763 case PAM_AUTH_ERR: 764 debug3("PAM: %s", pam_strerror(sshpam_handle, type)); 765 if (**prompts != NULL && strlen(**prompts) != 0) { 766 *info = **prompts; 767 **prompts = NULL; 768 *num = 0; 769 **echo_on = 0; 770 ctxt->pam_done = -1; 771 free(msg); 772 return 0; 773 } 774 /* FALLTHROUGH */ 775 case PAM_SUCCESS: 776 if (**prompts != NULL) { 777 /* drain any accumulated messages */ 778 debug("PAM: %s", **prompts); 779 buffer_append(&loginmsg, **prompts, 780 strlen(**prompts)); 781 free(**prompts); 782 **prompts = NULL; 783 } 784 if (type == PAM_SUCCESS) { 785 if (!sshpam_authctxt->valid || 786 (sshpam_authctxt->pw->pw_uid == 0 && 787 options.permit_root_login != PERMIT_YES)) 788 fatal("Internal error: PAM auth " 789 "succeeded when it should have " 790 "failed"); 791 import_environments(&buffer); 792 *num = 0; 793 **echo_on = 0; 794 ctxt->pam_done = 1; 795 free(msg); 796 return (0); 797 } 798 BLACKLIST_NOTIFY(BLACKLIST_BAD_USER, 799 sshpam_authctxt->user); 800 error("PAM: %s for %s%.100s from %.100s", msg, 801 sshpam_authctxt->valid ? "" : "illegal user ", 802 sshpam_authctxt->user, 803 get_remote_name_or_ip(utmp_len, options.use_dns)); 804 /* FALLTHROUGH */ 805 default: 806 *num = 0; 807 **echo_on = 0; 808 free(msg); 809 ctxt->pam_done = -1; 810 return (-1); 811 } 812 } 813 return (-1); 814} 815 816/* XXX - see also comment in auth-chall.c:verify_response */ 817static int 818sshpam_respond(void *ctx, u_int num, char **resp) 819{ 820 Buffer buffer; 821 struct pam_ctxt *ctxt = ctx; 822 823 debug2("PAM: %s entering, %u responses", __func__, num); 824 switch (ctxt->pam_done) { 825 case 1: 826 sshpam_authenticated = 1; 827 return (0); 828 case 0: 829 break; 830 default: 831 return (-1); 832 } 833 if (num != 1) { 834 error("PAM: expected one response, got %u", num); 835 return (-1); 836 } 837 buffer_init(&buffer); 838 if (sshpam_authctxt->valid && 839 (sshpam_authctxt->pw->pw_uid != 0 || 840 options.permit_root_login == PERMIT_YES)) 841 buffer_put_cstring(&buffer, *resp); 842 else 843 buffer_put_cstring(&buffer, badpw); 844 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) { 845 buffer_free(&buffer); 846 return (-1); 847 } 848 buffer_free(&buffer); 849 return (1); 850} 851 852static void 853sshpam_free_ctx(void *ctxtp) 854{ 855 struct pam_ctxt *ctxt = ctxtp; 856 857 debug3("PAM: %s entering", __func__); 858 sshpam_thread_cleanup(); 859 free(ctxt); 860 /* 861 * We don't call sshpam_cleanup() here because we may need the PAM 862 * handle at a later stage, e.g. when setting up a session. It's 863 * still on the cleanup list, so pam_end() *will* be called before 864 * the server process terminates. 865 */ 866} 867 868KbdintDevice sshpam_device = { 869 "pam", 870 sshpam_init_ctx, 871 sshpam_query, 872 sshpam_respond, 873 sshpam_free_ctx 874}; 875 876KbdintDevice mm_sshpam_device = { 877 "pam", 878 mm_sshpam_init_ctx, 879 mm_sshpam_query, 880 mm_sshpam_respond, 881 mm_sshpam_free_ctx 882}; 883 884/* 885 * This replaces auth-pam.c 886 */ 887void 888start_pam(Authctxt *authctxt) 889{ 890 if (!options.use_pam) 891 fatal("PAM: initialisation requested when UsePAM=no"); 892 893 if (sshpam_init(authctxt) == -1) 894 fatal("PAM: initialisation failed"); 895} 896 897void 898finish_pam(void) 899{ 900 sshpam_cleanup(); 901} 902 903u_int 904do_pam_account(void) 905{ 906 debug("%s: called", __func__); 907 if (sshpam_account_status != -1) 908 return (sshpam_account_status); 909 910 sshpam_err = pam_acct_mgmt(sshpam_handle, 0); 911 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err, 912 pam_strerror(sshpam_handle, sshpam_err)); 913 914 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) { 915 sshpam_account_status = 0; 916 return (sshpam_account_status); 917 } 918 919 if (sshpam_err == PAM_NEW_AUTHTOK_REQD) 920 sshpam_password_change_required(1); 921 922 sshpam_account_status = 1; 923 return (sshpam_account_status); 924} 925 926void 927do_pam_set_tty(const char *tty) 928{ 929 if (tty != NULL) { 930 debug("PAM: setting PAM_TTY to \"%s\"", tty); 931 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty); 932 if (sshpam_err != PAM_SUCCESS) 933 fatal("PAM: failed to set PAM_TTY: %s", 934 pam_strerror(sshpam_handle, sshpam_err)); 935 } 936} 937 938void 939do_pam_setcred(int init) 940{ 941 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 942 (const void *)&store_conv); 943 if (sshpam_err != PAM_SUCCESS) 944 fatal("PAM: failed to set PAM_CONV: %s", 945 pam_strerror(sshpam_handle, sshpam_err)); 946 if (init) { 947 debug("PAM: establishing credentials"); 948 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED); 949 } else { 950 debug("PAM: reinitializing credentials"); 951 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED); 952 } 953 if (sshpam_err == PAM_SUCCESS) { 954 sshpam_cred_established = 1; 955 return; 956 } 957 if (sshpam_authenticated) 958 fatal("PAM: pam_setcred(): %s", 959 pam_strerror(sshpam_handle, sshpam_err)); 960 else 961 debug("PAM: pam_setcred(): %s", 962 pam_strerror(sshpam_handle, sshpam_err)); 963} 964 965static int 966sshpam_tty_conv(int n, sshpam_const struct pam_message **msg, 967 struct pam_response **resp, void *data) 968{ 969 char input[PAM_MAX_MSG_SIZE]; 970 struct pam_response *reply; 971 int i; 972 973 debug3("PAM: %s called with %d messages", __func__, n); 974 975 *resp = NULL; 976 977 if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO)) 978 return (PAM_CONV_ERR); 979 980 if ((reply = calloc(n, sizeof(*reply))) == NULL) 981 return (PAM_CONV_ERR); 982 983 for (i = 0; i < n; ++i) { 984 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 985 case PAM_PROMPT_ECHO_OFF: 986 reply[i].resp = 987 read_passphrase(PAM_MSG_MEMBER(msg, i, msg), 988 RP_ALLOW_STDIN); 989 reply[i].resp_retcode = PAM_SUCCESS; 990 break; 991 case PAM_PROMPT_ECHO_ON: 992 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 993 if (fgets(input, sizeof input, stdin) == NULL) 994 input[0] = '\0'; 995 if ((reply[i].resp = strdup(input)) == NULL) 996 goto fail; 997 reply[i].resp_retcode = PAM_SUCCESS; 998 break; 999 case PAM_ERROR_MSG: 1000 case PAM_TEXT_INFO: 1001 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1002 reply[i].resp_retcode = PAM_SUCCESS; 1003 break; 1004 default: 1005 goto fail; 1006 } 1007 } 1008 *resp = reply; 1009 return (PAM_SUCCESS); 1010 1011 fail: 1012 for(i = 0; i < n; i++) { 1013 free(reply[i].resp); 1014 } 1015 free(reply); 1016 return (PAM_CONV_ERR); 1017} 1018 1019static struct pam_conv tty_conv = { sshpam_tty_conv, NULL }; 1020 1021/* 1022 * XXX this should be done in the authentication phase, but ssh1 doesn't 1023 * support that 1024 */ 1025void 1026do_pam_chauthtok(void) 1027{ 1028 if (use_privsep) 1029 fatal("Password expired (unable to change with privsep)"); 1030 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1031 (const void *)&tty_conv); 1032 if (sshpam_err != PAM_SUCCESS) 1033 fatal("PAM: failed to set PAM_CONV: %s", 1034 pam_strerror(sshpam_handle, sshpam_err)); 1035 debug("PAM: changing password"); 1036 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK); 1037 if (sshpam_err != PAM_SUCCESS) 1038 fatal("PAM: pam_chauthtok(): %s", 1039 pam_strerror(sshpam_handle, sshpam_err)); 1040} 1041 1042void 1043do_pam_session(void) 1044{ 1045 debug3("PAM: opening session"); 1046 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1047 (const void *)&store_conv); 1048 if (sshpam_err != PAM_SUCCESS) 1049 fatal("PAM: failed to set PAM_CONV: %s", 1050 pam_strerror(sshpam_handle, sshpam_err)); 1051 sshpam_err = pam_open_session(sshpam_handle, 0); 1052 if (sshpam_err == PAM_SUCCESS) 1053 sshpam_session_open = 1; 1054 else { 1055 sshpam_session_open = 0; 1056 disable_forwarding(); 1057 error("PAM: pam_open_session(): %s", 1058 pam_strerror(sshpam_handle, sshpam_err)); 1059 } 1060 1061} 1062 1063int 1064is_pam_session_open(void) 1065{ 1066 return sshpam_session_open; 1067} 1068 1069/* 1070 * Set a PAM environment string. We need to do this so that the session 1071 * modules can handle things like Kerberos/GSI credentials that appear 1072 * during the ssh authentication process. 1073 */ 1074int 1075do_pam_putenv(char *name, char *value) 1076{ 1077 int ret = 1; 1078#ifdef HAVE_PAM_PUTENV 1079 char *compound; 1080 size_t len; 1081 1082 len = strlen(name) + strlen(value) + 2; 1083 compound = xmalloc(len); 1084 1085 snprintf(compound, len, "%s=%s", name, value); 1086 ret = pam_putenv(sshpam_handle, compound); 1087 free(compound); 1088#endif 1089 1090 return (ret); 1091} 1092 1093char ** 1094fetch_pam_child_environment(void) 1095{ 1096 return sshpam_env; 1097} 1098 1099char ** 1100fetch_pam_environment(void) 1101{ 1102 return (pam_getenvlist(sshpam_handle)); 1103} 1104 1105void 1106free_pam_environment(char **env) 1107{ 1108 char **envp; 1109 1110 if (env == NULL) 1111 return; 1112 1113 for (envp = env; *envp; envp++) 1114 free(*envp); 1115 free(env); 1116} 1117 1118/* 1119 * "Blind" conversation function for password authentication. Assumes that 1120 * echo-off prompts are for the password and stores messages for later 1121 * display. 1122 */ 1123static int 1124sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg, 1125 struct pam_response **resp, void *data) 1126{ 1127 struct pam_response *reply; 1128 int i; 1129 size_t len; 1130 1131 debug3("PAM: %s called with %d messages", __func__, n); 1132 1133 *resp = NULL; 1134 1135 if (n <= 0 || n > PAM_MAX_NUM_MSG) 1136 return (PAM_CONV_ERR); 1137 1138 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1139 return (PAM_CONV_ERR); 1140 1141 for (i = 0; i < n; ++i) { 1142 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1143 case PAM_PROMPT_ECHO_OFF: 1144 if (sshpam_password == NULL) 1145 goto fail; 1146 if ((reply[i].resp = strdup(sshpam_password)) == NULL) 1147 goto fail; 1148 reply[i].resp_retcode = PAM_SUCCESS; 1149 break; 1150 case PAM_ERROR_MSG: 1151 case PAM_TEXT_INFO: 1152 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 1153 if (len > 0) { 1154 buffer_append(&loginmsg, 1155 PAM_MSG_MEMBER(msg, i, msg), len); 1156 buffer_append(&loginmsg, "\n", 1); 1157 } 1158 if ((reply[i].resp = strdup("")) == NULL) 1159 goto fail; 1160 reply[i].resp_retcode = PAM_SUCCESS; 1161 break; 1162 default: 1163 goto fail; 1164 } 1165 } 1166 *resp = reply; 1167 return (PAM_SUCCESS); 1168 1169 fail: 1170 for(i = 0; i < n; i++) { 1171 free(reply[i].resp); 1172 } 1173 free(reply); 1174 return (PAM_CONV_ERR); 1175} 1176 1177static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL }; 1178 1179/* 1180 * Attempt password authentication via PAM 1181 */ 1182int 1183sshpam_auth_passwd(Authctxt *authctxt, const char *password) 1184{ 1185 int flags = (options.permit_empty_passwd == 0 ? 1186 PAM_DISALLOW_NULL_AUTHTOK : 0); 1187 1188 if (!options.use_pam || sshpam_handle == NULL) 1189 fatal("PAM: %s called when PAM disabled or failed to " 1190 "initialise.", __func__); 1191 1192 sshpam_password = password; 1193 sshpam_authctxt = authctxt; 1194 1195 /* 1196 * If the user logging in is invalid, or is root but is not permitted 1197 * by PermitRootLogin, use an invalid password to prevent leaking 1198 * information via timing (eg if the PAM config has a delay on fail). 1199 */ 1200 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 && 1201 options.permit_root_login != PERMIT_YES)) 1202 sshpam_password = badpw; 1203 1204 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1205 (const void *)&passwd_conv); 1206 if (sshpam_err != PAM_SUCCESS) 1207 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__, 1208 pam_strerror(sshpam_handle, sshpam_err)); 1209 1210 sshpam_err = pam_authenticate(sshpam_handle, flags); 1211 sshpam_password = NULL; 1212 if (sshpam_err == PAM_SUCCESS && authctxt->valid) { 1213 debug("PAM: password authentication accepted for %.100s", 1214 authctxt->user); 1215 return 1; 1216 } else { 1217 debug("PAM: password authentication failed for %.100s: %s", 1218 authctxt->valid ? authctxt->user : "an illegal user", 1219 pam_strerror(sshpam_handle, sshpam_err)); 1220 return 0; 1221 } 1222} 1223#endif /* USE_PAM */ 1224