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 Exp $ */ 49 #include "includes.h" 50 /* 51 * NetBSD local changes 52 */ 53 __RCSID("$NetBSD: auth-pam.c,v 1.4 2013/11/08 19:18:24 christos Exp $"); 54 #undef USE_POSIX_THREADS /* Not yet */ 55 #define HAVE_SECURITY_PAM_APPL_H 56 #define HAVE_PAM_GETENVLIST 57 #define HAVE_PAM_PUTENV 58 #define sshpam_const const /* LinuxPAM, OpenPAM */ 59 #define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member) 60 #define mysig_t sig_t 61 void sshpam_password_change_required(int); 62 /* end NetBSD local changes */ 63 64 #include <sys/types.h> 65 #include <sys/stat.h> 66 #include <sys/wait.h> 67 #include <sys/socket.h> 68 69 #include <errno.h> 70 #include <signal.h> 71 #include <stdarg.h> 72 #include <string.h> 73 #include <unistd.h> 74 #include <pwd.h> 75 76 #ifdef USE_PAM 77 #if defined(HAVE_SECURITY_PAM_APPL_H) 78 #include <security/pam_appl.h> 79 #elif defined (HAVE_PAM_PAM_APPL_H) 80 #include <pam/pam_appl.h> 81 #endif 82 83 #ifndef __NetBSD__ 84 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */ 85 #ifdef PAM_SUN_CODEBASE 86 # define sshpam_const /* Solaris, HP-UX, AIX */ 87 #else 88 # define sshpam_const const /* LinuxPAM, OpenPAM */ 89 #endif 90 91 /* Ambiguity in spec: is it an array of pointers or a pointer to an array? */ 92 #ifdef PAM_SUN_CODEBASE 93 # define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member) 94 #else 95 # define PAM_MSG_MEMBER(msg, n, member) ((msg)[(n)]->member) 96 #endif 97 #endif 98 99 #include "xmalloc.h" 100 #include "buffer.h" 101 #include "key.h" 102 #include "hostfile.h" 103 #include "auth.h" 104 #include "auth-pam.h" 105 #include "canohost.h" 106 #include "log.h" 107 #include "msg.h" 108 #include "packet.h" 109 #include "misc.h" 110 #include "servconf.h" 111 #include "ssh2.h" 112 #include "auth-options.h" 113 #ifdef GSSAPI 114 #include "ssh-gss.h" 115 #endif 116 #include "monitor_wrap.h" 117 118 extern ServerOptions options; 119 extern Buffer loginmsg; 120 extern int compat20; 121 extern u_int utmp_len; 122 123 /* so we don't silently change behaviour */ 124 #ifdef USE_POSIX_THREADS 125 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK" 126 #endif 127 128 /* 129 * Formerly known as USE_POSIX_THREADS, using this is completely unsupported 130 * and generally a bad idea. Use at own risk and do not expect support if 131 * this breaks. 132 */ 133 #ifdef UNSUPPORTED_POSIX_THREADS_HACK 134 #include <pthread.h> 135 /* 136 * Avoid namespace clash when *not* using pthreads for systems *with* 137 * pthreads, which unconditionally define pthread_t via sys/types.h 138 * (e.g. Linux) 139 */ 140 typedef pthread_t sp_pthread_t; 141 #else 142 typedef pid_t sp_pthread_t; 143 #endif 144 145 struct pam_ctxt { 146 sp_pthread_t pam_thread; 147 int pam_psock; 148 int pam_csock; 149 int pam_done; 150 }; 151 152 static void sshpam_free_ctx(void *); 153 static struct pam_ctxt *cleanup_ctxt; 154 155 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 156 /* 157 * Simulate threads with processes. 158 */ 159 160 static int sshpam_thread_status = -1; 161 static mysig_t sshpam_oldsig; 162 163 static void 164 sshpam_sigchld_handler(int sig) 165 { 166 signal(SIGCHLD, SIG_DFL); 167 if (cleanup_ctxt == NULL) 168 return; /* handler called after PAM cleanup, shouldn't happen */ 169 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG) 170 <= 0) { 171 /* PAM thread has not exitted, privsep slave must have */ 172 kill(cleanup_ctxt->pam_thread, SIGTERM); 173 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, 0) 174 <= 0) 175 return; /* could not wait */ 176 } 177 if (WIFSIGNALED(sshpam_thread_status) && 178 WTERMSIG(sshpam_thread_status) == SIGTERM) 179 return; /* terminated by pthread_cancel */ 180 if (!WIFEXITED(sshpam_thread_status)) 181 sigdie("PAM: authentication thread exited unexpectedly"); 182 if (WEXITSTATUS(sshpam_thread_status) != 0) 183 sigdie("PAM: authentication thread exited uncleanly"); 184 } 185 186 /* ARGSUSED */ 187 __dead static void 188 pthread_exit(void *value) 189 { 190 _exit(0); 191 } 192 193 /* ARGSUSED */ 194 static int 195 pthread_create(sp_pthread_t *thread, const void *attr, 196 void *(*thread_start)(void *), void *arg) 197 { 198 pid_t pid; 199 struct pam_ctxt *ctx = arg; 200 201 sshpam_thread_status = -1; 202 switch ((pid = fork())) { 203 case -1: 204 error("fork(): %s", strerror(errno)); 205 return (-1); 206 case 0: 207 close(ctx->pam_psock); 208 ctx->pam_psock = -1; 209 thread_start(arg); 210 _exit(1); 211 default: 212 *thread = pid; 213 close(ctx->pam_csock); 214 ctx->pam_csock = -1; 215 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler); 216 return (0); 217 } 218 } 219 220 static int 221 pthread_cancel(sp_pthread_t thread) 222 { 223 signal(SIGCHLD, sshpam_oldsig); 224 return (kill(thread, SIGTERM)); 225 } 226 227 /* ARGSUSED */ 228 static int 229 pthread_join(sp_pthread_t thread, void **value) 230 { 231 int status; 232 233 if (sshpam_thread_status != -1) 234 return (sshpam_thread_status); 235 signal(SIGCHLD, sshpam_oldsig); 236 waitpid(thread, &status, 0); 237 return (status); 238 } 239 #endif 240 241 242 static pam_handle_t *sshpam_handle = NULL; 243 static int sshpam_err = 0; 244 static int sshpam_authenticated = 0; 245 static int sshpam_session_open = 0; 246 static int sshpam_cred_established = 0; 247 static int sshpam_account_status = -1; 248 static char **sshpam_env = NULL; 249 static Authctxt *sshpam_authctxt = NULL; 250 static const char *sshpam_password = NULL; 251 static char badpw[] = "\b\n\r\177INCORRECT"; 252 253 /* Some PAM implementations don't implement this */ 254 #ifndef HAVE_PAM_GETENVLIST 255 static char ** 256 pam_getenvlist(pam_handle_t *pamh) 257 { 258 /* 259 * XXX - If necessary, we can still support envrionment passing 260 * for platforms without pam_getenvlist by searching for known 261 * env vars (e.g. KRB5CCNAME) from the PAM environment. 262 */ 263 return NULL; 264 } 265 #endif 266 267 /* 268 * Some platforms, notably Solaris, do not enforce password complexity 269 * rules during pam_chauthtok() if the real uid of the calling process 270 * is 0, on the assumption that it's being called by "passwd" run by root. 271 * This wraps pam_chauthtok and sets/restore the real uid so PAM will do 272 * the right thing. 273 */ 274 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID 275 static int 276 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags) 277 { 278 int result; 279 280 if (sshpam_authctxt == NULL) 281 fatal("PAM: sshpam_authctxt not initialized"); 282 if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1) 283 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 284 result = pam_chauthtok(pamh, flags); 285 if (setreuid(0, -1) == -1) 286 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 287 return result; 288 } 289 # define pam_chauthtok(a,b) (sshpam_chauthtok_ruid((a), (b))) 290 #endif 291 292 void 293 sshpam_password_change_required(int reqd) 294 { 295 debug3("%s %d", __func__, reqd); 296 if (sshpam_authctxt == NULL) 297 fatal("%s: PAM authctxt not initialized", __func__); 298 sshpam_authctxt->force_pwchange = reqd; 299 if (reqd) { 300 no_port_forwarding_flag |= 2; 301 no_agent_forwarding_flag |= 2; 302 no_x11_forwarding_flag |= 2; 303 } else { 304 no_port_forwarding_flag &= ~2; 305 no_agent_forwarding_flag &= ~2; 306 no_x11_forwarding_flag &= ~2; 307 } 308 } 309 310 /* Import regular and PAM environment from subprocess */ 311 static void 312 import_environments(Buffer *b) 313 { 314 char *env; 315 u_int i, num_env; 316 int err; 317 318 debug3("PAM: %s entering", __func__); 319 320 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 321 /* Import variables set by do_pam_account */ 322 sshpam_account_status = buffer_get_int(b); 323 sshpam_password_change_required(buffer_get_int(b)); 324 325 /* Import environment from subprocess */ 326 num_env = buffer_get_int(b); 327 if (num_env > 1024) 328 fatal("%s: received %u environment variables, expected <= 1024", 329 __func__, num_env); 330 sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env)); 331 debug3("PAM: num env strings %d", num_env); 332 for(i = 0; i < num_env; i++) 333 sshpam_env[i] = buffer_get_string(b, NULL); 334 335 sshpam_env[num_env] = NULL; 336 337 /* Import PAM environment from subprocess */ 338 num_env = buffer_get_int(b); 339 debug("PAM: num PAM env strings %d", num_env); 340 for(i = 0; i < num_env; i++) { 341 env = buffer_get_string(b, NULL); 342 343 #ifdef HAVE_PAM_PUTENV 344 /* Errors are not fatal here */ 345 if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) { 346 error("PAM: pam_putenv: %s", 347 pam_strerror(sshpam_handle, sshpam_err)); 348 } 349 #endif 350 } 351 #endif 352 } 353 354 /* 355 * Conversation function for authentication thread. 356 */ 357 static int 358 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg, 359 struct pam_response **resp, void *data) 360 { 361 Buffer buffer; 362 struct pam_ctxt *ctxt; 363 struct pam_response *reply; 364 int i; 365 366 debug3("PAM: %s entering, %d messages", __func__, n); 367 *resp = NULL; 368 369 if (data == NULL) { 370 error("PAM: conversation function passed a null context"); 371 return (PAM_CONV_ERR); 372 } 373 ctxt = data; 374 if (n <= 0 || n > PAM_MAX_NUM_MSG) 375 return (PAM_CONV_ERR); 376 377 if ((reply = calloc(n, sizeof(*reply))) == NULL) 378 return (PAM_CONV_ERR); 379 380 buffer_init(&buffer); 381 for (i = 0; i < n; ++i) { 382 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 383 case PAM_PROMPT_ECHO_OFF: 384 buffer_put_cstring(&buffer, 385 PAM_MSG_MEMBER(msg, i, msg)); 386 if (ssh_msg_send(ctxt->pam_csock, 387 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1) 388 goto fail; 389 if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1) 390 goto fail; 391 if (buffer_get_char(&buffer) != PAM_AUTHTOK) 392 goto fail; 393 reply[i].resp = buffer_get_string(&buffer, NULL); 394 break; 395 case PAM_PROMPT_ECHO_ON: 396 buffer_put_cstring(&buffer, 397 PAM_MSG_MEMBER(msg, i, msg)); 398 if (ssh_msg_send(ctxt->pam_csock, 399 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1) 400 goto fail; 401 if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1) 402 goto fail; 403 if (buffer_get_char(&buffer) != PAM_AUTHTOK) 404 goto fail; 405 reply[i].resp = buffer_get_string(&buffer, NULL); 406 break; 407 case PAM_ERROR_MSG: 408 buffer_put_cstring(&buffer, 409 PAM_MSG_MEMBER(msg, i, msg)); 410 if (ssh_msg_send(ctxt->pam_csock, 411 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1) 412 goto fail; 413 break; 414 case PAM_TEXT_INFO: 415 buffer_put_cstring(&buffer, 416 PAM_MSG_MEMBER(msg, i, msg)); 417 if (ssh_msg_send(ctxt->pam_csock, 418 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1) 419 goto fail; 420 break; 421 default: 422 goto fail; 423 } 424 buffer_clear(&buffer); 425 } 426 buffer_free(&buffer); 427 *resp = reply; 428 return (PAM_SUCCESS); 429 430 fail: 431 for(i = 0; i < n; i++) { 432 if (reply[i].resp != NULL) 433 free(reply[i].resp); 434 } 435 free(reply); 436 buffer_free(&buffer); 437 return (PAM_CONV_ERR); 438 } 439 440 /* 441 * Authentication thread. 442 */ 443 static void * 444 sshpam_thread(void *ctxtp) 445 { 446 struct pam_ctxt *ctxt = ctxtp; 447 Buffer buffer; 448 struct pam_conv sshpam_conv; 449 int flags = (options.permit_empty_passwd == 0 ? 450 PAM_DISALLOW_NULL_AUTHTOK : 0); 451 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 452 extern char **environ; 453 char **env_from_pam; 454 u_int i; 455 const char *pam_user; 456 const char **ptr_pam_user = &pam_user; 457 char *tz = getenv("TZ"); 458 459 pam_get_item(sshpam_handle, PAM_USER, 460 (sshpam_const void **)ptr_pam_user); 461 462 environ[0] = NULL; 463 if (tz != NULL) 464 if (setenv("TZ", tz, 1) == -1) 465 error("PAM: could not set TZ environment: %s", 466 strerror(errno)); 467 468 if (sshpam_authctxt != NULL) { 469 setproctitle("%s [pam]", 470 sshpam_authctxt->valid ? pam_user : "unknown"); 471 } 472 #endif 473 474 sshpam_conv.conv = sshpam_thread_conv; 475 sshpam_conv.appdata_ptr = ctxt; 476 477 if (sshpam_authctxt == NULL) 478 fatal("%s: PAM authctxt not initialized", __func__); 479 480 buffer_init(&buffer); 481 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 482 (const void *)&sshpam_conv); 483 if (sshpam_err != PAM_SUCCESS) 484 goto auth_fail; 485 sshpam_err = pam_authenticate(sshpam_handle, flags); 486 if (sshpam_err != PAM_SUCCESS) 487 goto auth_fail; 488 489 if (compat20) { 490 if (!do_pam_account()) { 491 sshpam_err = PAM_ACCT_EXPIRED; 492 goto auth_fail; 493 } 494 if (sshpam_authctxt->force_pwchange) { 495 sshpam_err = pam_chauthtok(sshpam_handle, 496 PAM_CHANGE_EXPIRED_AUTHTOK); 497 if (sshpam_err != PAM_SUCCESS) 498 goto auth_fail; 499 sshpam_password_change_required(0); 500 } 501 } 502 503 buffer_put_cstring(&buffer, "OK"); 504 505 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 506 /* Export variables set by do_pam_account */ 507 buffer_put_int(&buffer, sshpam_account_status); 508 buffer_put_int(&buffer, sshpam_authctxt->force_pwchange); 509 510 /* Export any environment strings set in child */ 511 for(i = 0; environ[i] != NULL; i++) 512 ; /* Count */ 513 buffer_put_int(&buffer, i); 514 for(i = 0; environ[i] != NULL; i++) 515 buffer_put_cstring(&buffer, environ[i]); 516 517 /* Export any environment strings set by PAM in child */ 518 env_from_pam = pam_getenvlist(sshpam_handle); 519 for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) 520 ; /* Count */ 521 buffer_put_int(&buffer, i); 522 for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) 523 buffer_put_cstring(&buffer, env_from_pam[i]); 524 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */ 525 526 /* XXX - can't do much about an error here */ 527 ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer); 528 buffer_free(&buffer); 529 pthread_exit(NULL); 530 531 auth_fail: 532 buffer_put_cstring(&buffer, 533 pam_strerror(sshpam_handle, sshpam_err)); 534 /* XXX - can't do much about an error here */ 535 if (sshpam_err == PAM_ACCT_EXPIRED) 536 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, &buffer); 537 else 538 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer); 539 buffer_free(&buffer); 540 pthread_exit(NULL); 541 542 return (NULL); /* Avoid warning for non-pthread case */ 543 } 544 545 void 546 sshpam_thread_cleanup(void) 547 { 548 struct pam_ctxt *ctxt = cleanup_ctxt; 549 550 debug3("PAM: %s entering", __func__); 551 if (ctxt != NULL && ctxt->pam_thread != 0) { 552 pthread_cancel(ctxt->pam_thread); 553 pthread_join(ctxt->pam_thread, NULL); 554 close(ctxt->pam_psock); 555 close(ctxt->pam_csock); 556 memset(ctxt, 0, sizeof(*ctxt)); 557 cleanup_ctxt = NULL; 558 } 559 } 560 561 static int 562 sshpam_null_conv(int n, sshpam_const struct pam_message **msg, 563 struct pam_response **resp, void *data) 564 { 565 debug3("PAM: %s entering, %d messages", __func__, n); 566 return (PAM_CONV_ERR); 567 } 568 569 static struct pam_conv null_conv = { sshpam_null_conv, NULL }; 570 571 static int 572 sshpam_store_conv(int n, sshpam_const struct pam_message **msg, 573 struct pam_response **resp, void *data) 574 { 575 struct pam_response *reply; 576 int i; 577 size_t len; 578 579 debug3("PAM: %s called with %d messages", __func__, n); 580 *resp = NULL; 581 582 if (n <= 0 || n > PAM_MAX_NUM_MSG) 583 return (PAM_CONV_ERR); 584 585 if ((reply = calloc(n, sizeof(*reply))) == NULL) 586 return (PAM_CONV_ERR); 587 588 for (i = 0; i < n; ++i) { 589 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 590 case PAM_ERROR_MSG: 591 case PAM_TEXT_INFO: 592 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 593 buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len); 594 buffer_append(&loginmsg, "\n", 1 ); 595 reply[i].resp_retcode = PAM_SUCCESS; 596 break; 597 default: 598 goto fail; 599 } 600 } 601 *resp = reply; 602 return (PAM_SUCCESS); 603 604 fail: 605 for(i = 0; i < n; i++) { 606 if (reply[i].resp != NULL) 607 free(reply[i].resp); 608 } 609 free(reply); 610 return (PAM_CONV_ERR); 611 } 612 613 static struct pam_conv store_conv = { sshpam_store_conv, NULL }; 614 615 void 616 sshpam_cleanup(void) 617 { 618 if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor())) 619 return; 620 debug("PAM: cleanup"); 621 pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv); 622 if (sshpam_session_open) { 623 debug("PAM: closing session"); 624 pam_close_session(sshpam_handle, PAM_SILENT); 625 sshpam_session_open = 0; 626 } 627 if (sshpam_cred_established) { 628 debug("PAM: deleting credentials"); 629 pam_setcred(sshpam_handle, PAM_DELETE_CRED); 630 sshpam_cred_established = 0; 631 } 632 sshpam_authenticated = 0; 633 pam_end(sshpam_handle, sshpam_err); 634 sshpam_handle = NULL; 635 } 636 637 static int 638 sshpam_init(Authctxt *authctxt) 639 { 640 const char *pam_rhost, *pam_user, *user = authctxt->user; 641 const char **ptr_pam_user = &pam_user; 642 643 if (sshpam_handle != NULL) { 644 /* We already have a PAM context; check if the user matches */ 645 sshpam_err = pam_get_item(sshpam_handle, 646 PAM_USER, (sshpam_const void **)ptr_pam_user); 647 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0) 648 return (0); 649 pam_end(sshpam_handle, sshpam_err); 650 sshpam_handle = NULL; 651 } 652 debug("PAM: initializing for \"%s\"", user); 653 sshpam_err = 654 pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle); 655 sshpam_authctxt = authctxt; 656 657 if (sshpam_err != PAM_SUCCESS) { 658 pam_end(sshpam_handle, sshpam_err); 659 sshpam_handle = NULL; 660 return (-1); 661 } 662 pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns); 663 debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost); 664 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost); 665 if (sshpam_err != PAM_SUCCESS) { 666 pam_end(sshpam_handle, sshpam_err); 667 sshpam_handle = NULL; 668 return (-1); 669 } 670 #ifdef PAM_TTY_KLUDGE 671 /* 672 * Some silly PAM modules (e.g. pam_time) require a TTY to operate. 673 * sshd doesn't set the tty until too late in the auth process and 674 * may not even set one (for tty-less connections) 675 */ 676 debug("PAM: setting PAM_TTY to \"ssh\""); 677 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh"); 678 if (sshpam_err != PAM_SUCCESS) { 679 pam_end(sshpam_handle, sshpam_err); 680 sshpam_handle = NULL; 681 return (-1); 682 } 683 #endif 684 return (0); 685 } 686 687 static void * 688 sshpam_init_ctx(Authctxt *authctxt) 689 { 690 struct pam_ctxt *ctxt; 691 int socks[2]; 692 693 debug3("PAM: %s entering", __func__); 694 /* 695 * Refuse to start if we don't have PAM enabled or do_pam_account 696 * has previously failed. 697 */ 698 if (!options.use_pam || sshpam_account_status == 0) 699 return NULL; 700 701 /* Initialize PAM */ 702 if (sshpam_init(authctxt) == -1) { 703 error("PAM: initialization failed"); 704 return (NULL); 705 } 706 707 ctxt = xcalloc(1, sizeof *ctxt); 708 709 /* Start the authentication thread */ 710 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) { 711 error("PAM: failed create sockets: %s", strerror(errno)); 712 free(ctxt); 713 return (NULL); 714 } 715 ctxt->pam_psock = socks[0]; 716 ctxt->pam_csock = socks[1]; 717 if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) { 718 error("PAM: failed to start authentication thread: %s", 719 strerror(errno)); 720 close(socks[0]); 721 close(socks[1]); 722 free(ctxt); 723 return (NULL); 724 } 725 cleanup_ctxt = ctxt; 726 return (ctxt); 727 } 728 729 static int 730 sshpam_query(void *ctx, char **name, char **info, 731 u_int *num, char ***prompts, u_int **echo_on) 732 { 733 Buffer buffer; 734 struct pam_ctxt *ctxt = ctx; 735 size_t plen; 736 u_char type; 737 char *msg; 738 size_t len, mlen; 739 740 debug3("PAM: %s entering", __func__); 741 buffer_init(&buffer); 742 *name = xstrdup(""); 743 *info = xstrdup(""); 744 *prompts = xmalloc(sizeof(char *)); 745 **prompts = NULL; 746 plen = 0; 747 *echo_on = xmalloc(sizeof(u_int)); 748 while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) { 749 type = buffer_get_char(&buffer); 750 msg = buffer_get_string(&buffer, NULL); 751 mlen = strlen(msg); 752 switch (type) { 753 case PAM_PROMPT_ECHO_ON: 754 case PAM_PROMPT_ECHO_OFF: 755 *num = 1; 756 len = plen + mlen + 1; 757 **prompts = xrealloc(**prompts, 1, len); 758 strlcpy(**prompts + plen, msg, len - plen); 759 plen += mlen; 760 **echo_on = (type == PAM_PROMPT_ECHO_ON); 761 free(msg); 762 return (0); 763 case PAM_ERROR_MSG: 764 case PAM_TEXT_INFO: 765 /* accumulate messages */ 766 len = plen + mlen + 2; 767 **prompts = xrealloc(**prompts, 1, len); 768 strlcpy(**prompts + plen, msg, len - plen); 769 plen += mlen; 770 strlcat(**prompts + plen, "\n", len - plen); 771 plen++; 772 free(msg); 773 break; 774 case PAM_ACCT_EXPIRED: 775 sshpam_account_status = 0; 776 /* FALLTHROUGH */ 777 case PAM_AUTH_ERR: 778 debug3("PAM: %s", pam_strerror(sshpam_handle, type)); 779 if (**prompts != NULL && strlen(**prompts) != 0) { 780 *info = **prompts; 781 **prompts = NULL; 782 *num = 0; 783 **echo_on = 0; 784 ctxt->pam_done = -1; 785 free(msg); 786 return 0; 787 } 788 /* FALLTHROUGH */ 789 case PAM_SUCCESS: 790 if (**prompts != NULL) { 791 /* drain any accumulated messages */ 792 debug("PAM: %s", **prompts); 793 buffer_append(&loginmsg, **prompts, 794 strlen(**prompts)); 795 free(**prompts); 796 **prompts = NULL; 797 } 798 if (type == PAM_SUCCESS) { 799 if (!sshpam_authctxt->valid || 800 (sshpam_authctxt->pw->pw_uid == 0 && 801 options.permit_root_login != PERMIT_YES)) 802 fatal("Internal error: PAM auth " 803 "succeeded when it should have " 804 "failed"); 805 import_environments(&buffer); 806 *num = 0; 807 **echo_on = 0; 808 ctxt->pam_done = 1; 809 free(msg); 810 return (0); 811 } 812 error("PAM: %s for %s%.100s from %.100s", msg, 813 sshpam_authctxt->valid ? "" : "illegal user ", 814 sshpam_authctxt->user, 815 get_remote_name_or_ip(utmp_len, options.use_dns)); 816 /* FALLTHROUGH */ 817 default: 818 *num = 0; 819 **echo_on = 0; 820 free(msg); 821 ctxt->pam_done = -1; 822 return (-1); 823 } 824 } 825 return (-1); 826 } 827 828 /* XXX - see also comment in auth-chall.c:verify_response */ 829 static int 830 sshpam_respond(void *ctx, u_int num, char **resp) 831 { 832 Buffer buffer; 833 struct pam_ctxt *ctxt = ctx; 834 835 debug2("PAM: %s entering, %u responses", __func__, num); 836 switch (ctxt->pam_done) { 837 case 1: 838 sshpam_authenticated = 1; 839 return (0); 840 case 0: 841 break; 842 default: 843 return (-1); 844 } 845 if (num != 1) { 846 error("PAM: expected one response, got %u", num); 847 return (-1); 848 } 849 buffer_init(&buffer); 850 if (sshpam_authctxt->valid && 851 (sshpam_authctxt->pw->pw_uid != 0 || 852 options.permit_root_login == PERMIT_YES)) 853 buffer_put_cstring(&buffer, *resp); 854 else 855 buffer_put_cstring(&buffer, badpw); 856 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) { 857 buffer_free(&buffer); 858 return (-1); 859 } 860 buffer_free(&buffer); 861 return (1); 862 } 863 864 static void 865 sshpam_free_ctx(void *ctxtp) 866 { 867 struct pam_ctxt *ctxt = ctxtp; 868 869 debug3("PAM: %s entering", __func__); 870 sshpam_thread_cleanup(); 871 free(ctxt); 872 /* 873 * We don't call sshpam_cleanup() here because we may need the PAM 874 * handle at a later stage, e.g. when setting up a session. It's 875 * still on the cleanup list, so pam_end() *will* be called before 876 * the server process terminates. 877 */ 878 } 879 880 KbdintDevice sshpam_device = { 881 "pam", 882 sshpam_init_ctx, 883 sshpam_query, 884 sshpam_respond, 885 sshpam_free_ctx 886 }; 887 888 KbdintDevice mm_sshpam_device = { 889 "pam", 890 mm_sshpam_init_ctx, 891 mm_sshpam_query, 892 mm_sshpam_respond, 893 mm_sshpam_free_ctx 894 }; 895 896 /* 897 * This replaces auth-pam.c 898 */ 899 void 900 start_pam(Authctxt *authctxt) 901 { 902 if (!options.use_pam) 903 fatal("PAM: initialisation requested when UsePAM=no"); 904 905 if (sshpam_init(authctxt) == -1) 906 fatal("PAM: initialisation failed"); 907 } 908 909 void 910 finish_pam(void) 911 { 912 sshpam_cleanup(); 913 } 914 915 u_int 916 do_pam_account(void) 917 { 918 debug("%s: called", __func__); 919 if (sshpam_account_status != -1) 920 return (sshpam_account_status); 921 922 sshpam_err = pam_acct_mgmt(sshpam_handle, 0); 923 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err, 924 pam_strerror(sshpam_handle, sshpam_err)); 925 926 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) { 927 sshpam_account_status = 0; 928 return (sshpam_account_status); 929 } 930 931 if (sshpam_err == PAM_NEW_AUTHTOK_REQD) 932 sshpam_password_change_required(1); 933 934 sshpam_account_status = 1; 935 return (sshpam_account_status); 936 } 937 938 void 939 do_pam_set_tty(const char *tty) 940 { 941 if (tty != NULL) { 942 debug("PAM: setting PAM_TTY to \"%s\"", tty); 943 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty); 944 if (sshpam_err != PAM_SUCCESS) 945 fatal("PAM: failed to set PAM_TTY: %s", 946 pam_strerror(sshpam_handle, sshpam_err)); 947 } 948 } 949 950 void 951 do_pam_setcred(int init) 952 { 953 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 954 (const void *)&store_conv); 955 if (sshpam_err != PAM_SUCCESS) 956 fatal("PAM: failed to set PAM_CONV: %s", 957 pam_strerror(sshpam_handle, sshpam_err)); 958 if (init) { 959 debug("PAM: establishing credentials"); 960 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED); 961 } else { 962 debug("PAM: reinitializing credentials"); 963 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED); 964 } 965 if (sshpam_err == PAM_SUCCESS) { 966 sshpam_cred_established = 1; 967 return; 968 } 969 if (sshpam_authenticated) 970 fatal("PAM: pam_setcred(): %s", 971 pam_strerror(sshpam_handle, sshpam_err)); 972 else 973 debug("PAM: pam_setcred(): %s", 974 pam_strerror(sshpam_handle, sshpam_err)); 975 } 976 977 static int 978 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg, 979 struct pam_response **resp, void *data) 980 { 981 char input[PAM_MAX_MSG_SIZE]; 982 struct pam_response *reply; 983 int i; 984 985 debug3("PAM: %s called with %d messages", __func__, n); 986 987 *resp = NULL; 988 989 if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO)) 990 return (PAM_CONV_ERR); 991 992 if ((reply = calloc(n, sizeof(*reply))) == NULL) 993 return (PAM_CONV_ERR); 994 995 for (i = 0; i < n; ++i) { 996 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 997 case PAM_PROMPT_ECHO_OFF: 998 reply[i].resp = 999 read_passphrase(PAM_MSG_MEMBER(msg, i, msg), 1000 RP_ALLOW_STDIN); 1001 reply[i].resp_retcode = PAM_SUCCESS; 1002 break; 1003 case PAM_PROMPT_ECHO_ON: 1004 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1005 if (fgets(input, sizeof input, stdin) == NULL) 1006 input[0] = '\0'; 1007 if ((reply[i].resp = strdup(input)) == NULL) 1008 goto fail; 1009 reply[i].resp_retcode = PAM_SUCCESS; 1010 break; 1011 case PAM_ERROR_MSG: 1012 case PAM_TEXT_INFO: 1013 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1014 reply[i].resp_retcode = PAM_SUCCESS; 1015 break; 1016 default: 1017 goto fail; 1018 } 1019 } 1020 *resp = reply; 1021 return (PAM_SUCCESS); 1022 1023 fail: 1024 for(i = 0; i < n; i++) { 1025 if (reply[i].resp != NULL) 1026 free(reply[i].resp); 1027 } 1028 free(reply); 1029 return (PAM_CONV_ERR); 1030 } 1031 1032 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL }; 1033 1034 /* 1035 * XXX this should be done in the authentication phase, but ssh1 doesn't 1036 * support that 1037 */ 1038 void 1039 do_pam_chauthtok(void) 1040 { 1041 if (use_privsep) 1042 fatal("Password expired (unable to change with privsep)"); 1043 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1044 (const void *)&tty_conv); 1045 if (sshpam_err != PAM_SUCCESS) 1046 fatal("PAM: failed to set PAM_CONV: %s", 1047 pam_strerror(sshpam_handle, sshpam_err)); 1048 debug("PAM: changing password"); 1049 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK); 1050 if (sshpam_err != PAM_SUCCESS) 1051 fatal("PAM: pam_chauthtok(): %s", 1052 pam_strerror(sshpam_handle, sshpam_err)); 1053 } 1054 1055 void 1056 do_pam_session(void) 1057 { 1058 debug3("PAM: opening session"); 1059 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1060 (const void *)&store_conv); 1061 if (sshpam_err != PAM_SUCCESS) 1062 fatal("PAM: failed to set PAM_CONV: %s", 1063 pam_strerror(sshpam_handle, sshpam_err)); 1064 sshpam_err = pam_open_session(sshpam_handle, 0); 1065 if (sshpam_err == PAM_SUCCESS) 1066 sshpam_session_open = 1; 1067 else { 1068 sshpam_session_open = 0; 1069 disable_forwarding(); 1070 error("PAM: pam_open_session(): %s", 1071 pam_strerror(sshpam_handle, sshpam_err)); 1072 } 1073 1074 } 1075 1076 int 1077 is_pam_session_open(void) 1078 { 1079 return sshpam_session_open; 1080 } 1081 1082 /* 1083 * Set a PAM environment string. We need to do this so that the session 1084 * modules can handle things like Kerberos/GSI credentials that appear 1085 * during the ssh authentication process. 1086 */ 1087 int 1088 do_pam_putenv(char *name, char *value) 1089 { 1090 int ret = 1; 1091 #ifdef HAVE_PAM_PUTENV 1092 char *compound; 1093 size_t len; 1094 1095 len = strlen(name) + strlen(value) + 2; 1096 compound = xmalloc(len); 1097 1098 snprintf(compound, len, "%s=%s", name, value); 1099 ret = pam_putenv(sshpam_handle, compound); 1100 free(compound); 1101 #endif 1102 1103 return (ret); 1104 } 1105 1106 char ** 1107 fetch_pam_child_environment(void) 1108 { 1109 return sshpam_env; 1110 } 1111 1112 char ** 1113 fetch_pam_environment(void) 1114 { 1115 return (pam_getenvlist(sshpam_handle)); 1116 } 1117 1118 void 1119 free_pam_environment(char **env) 1120 { 1121 char **envp; 1122 1123 if (env == NULL) 1124 return; 1125 1126 for (envp = env; *envp; envp++) 1127 free(*envp); 1128 free(env); 1129 } 1130 1131 /* 1132 * "Blind" conversation function for password authentication. Assumes that 1133 * echo-off prompts are for the password and stores messages for later 1134 * display. 1135 */ 1136 static int 1137 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg, 1138 struct pam_response **resp, void *data) 1139 { 1140 struct pam_response *reply; 1141 int i; 1142 size_t len; 1143 1144 debug3("PAM: %s called with %d messages", __func__, n); 1145 1146 *resp = NULL; 1147 1148 if (n <= 0 || n > PAM_MAX_NUM_MSG) 1149 return (PAM_CONV_ERR); 1150 1151 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1152 return (PAM_CONV_ERR); 1153 1154 for (i = 0; i < n; ++i) { 1155 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1156 case PAM_PROMPT_ECHO_OFF: 1157 if (sshpam_password == NULL) 1158 goto fail; 1159 if ((reply[i].resp = strdup(sshpam_password)) == NULL) 1160 goto fail; 1161 reply[i].resp_retcode = PAM_SUCCESS; 1162 break; 1163 case PAM_ERROR_MSG: 1164 case PAM_TEXT_INFO: 1165 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 1166 if (len > 0) { 1167 buffer_append(&loginmsg, 1168 PAM_MSG_MEMBER(msg, i, msg), len); 1169 buffer_append(&loginmsg, "\n", 1); 1170 } 1171 if ((reply[i].resp = strdup("")) == NULL) 1172 goto fail; 1173 reply[i].resp_retcode = PAM_SUCCESS; 1174 break; 1175 default: 1176 goto fail; 1177 } 1178 } 1179 *resp = reply; 1180 return (PAM_SUCCESS); 1181 1182 fail: 1183 for(i = 0; i < n; i++) { 1184 if (reply[i].resp != NULL) 1185 free(reply[i].resp); 1186 } 1187 free(reply); 1188 return (PAM_CONV_ERR); 1189 } 1190 1191 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL }; 1192 1193 /* 1194 * Attempt password authentication via PAM 1195 */ 1196 int 1197 sshpam_auth_passwd(Authctxt *authctxt, const char *password) 1198 { 1199 int flags = (options.permit_empty_passwd == 0 ? 1200 PAM_DISALLOW_NULL_AUTHTOK : 0); 1201 1202 if (!options.use_pam || sshpam_handle == NULL) 1203 fatal("PAM: %s called when PAM disabled or failed to " 1204 "initialise.", __func__); 1205 1206 sshpam_password = password; 1207 sshpam_authctxt = authctxt; 1208 1209 /* 1210 * If the user logging in is invalid, or is root but is not permitted 1211 * by PermitRootLogin, use an invalid password to prevent leaking 1212 * information via timing (eg if the PAM config has a delay on fail). 1213 */ 1214 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 && 1215 options.permit_root_login != PERMIT_YES)) 1216 sshpam_password = badpw; 1217 1218 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1219 (const void *)&passwd_conv); 1220 if (sshpam_err != PAM_SUCCESS) 1221 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__, 1222 pam_strerror(sshpam_handle, sshpam_err)); 1223 1224 sshpam_err = pam_authenticate(sshpam_handle, flags); 1225 sshpam_password = NULL; 1226 if (sshpam_err == PAM_SUCCESS && authctxt->valid) { 1227 debug("PAM: password authentication accepted for %.100s", 1228 authctxt->user); 1229 return 1; 1230 } else { 1231 debug("PAM: password authentication failed for %.100s: %s", 1232 authctxt->valid ? authctxt->user : "an illegal user", 1233 pam_strerror(sshpam_handle, sshpam_err)); 1234 return 0; 1235 } 1236 } 1237 #endif /* USE_PAM */ 1238