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 #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 pam_get_item(sshpam_handle, PAM_USER, 442 (sshpam_const void **)ptr_pam_user); 443 444 environ[0] = NULL; 445 if (tz != NULL) 446 if (setenv("TZ", tz, 1) == -1) 447 error("PAM: could not set TZ environment: %s", 448 strerror(errno)); 449 450 if (sshpam_authctxt != NULL) { 451 setproctitle("%s [pam]", 452 sshpam_authctxt->valid ? pam_user : "unknown"); 453 } 454 #endif 455 456 sshpam_conv.conv = sshpam_thread_conv; 457 sshpam_conv.appdata_ptr = ctxt; 458 459 if (sshpam_authctxt == NULL) 460 fatal("%s: PAM authctxt not initialized", __func__); 461 462 buffer_init(&buffer); 463 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 464 (const void *)&sshpam_conv); 465 if (sshpam_err != PAM_SUCCESS) 466 goto auth_fail; 467 sshpam_err = pam_authenticate(sshpam_handle, flags); 468 if (sshpam_err != PAM_SUCCESS) 469 goto auth_fail; 470 471 if (compat20) { 472 if (!do_pam_account()) { 473 sshpam_err = PAM_ACCT_EXPIRED; 474 goto auth_fail; 475 } 476 if (sshpam_authctxt->force_pwchange) { 477 sshpam_err = pam_chauthtok(sshpam_handle, 478 PAM_CHANGE_EXPIRED_AUTHTOK); 479 if (sshpam_err != PAM_SUCCESS) 480 goto auth_fail; 481 sshpam_password_change_required(0); 482 } 483 } 484 485 buffer_put_cstring(&buffer, "OK"); 486 487 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 488 /* Export variables set by do_pam_account */ 489 buffer_put_int(&buffer, sshpam_account_status); 490 buffer_put_int(&buffer, sshpam_authctxt->force_pwchange); 491 492 /* Export any environment strings set in child */ 493 for(i = 0; environ[i] != NULL; i++) 494 ; /* Count */ 495 buffer_put_int(&buffer, i); 496 for(i = 0; environ[i] != NULL; i++) 497 buffer_put_cstring(&buffer, environ[i]); 498 499 /* Export any environment strings set by PAM in child */ 500 env_from_pam = pam_getenvlist(sshpam_handle); 501 for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) 502 ; /* Count */ 503 buffer_put_int(&buffer, i); 504 for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) 505 buffer_put_cstring(&buffer, env_from_pam[i]); 506 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */ 507 508 /* XXX - can't do much about an error here */ 509 ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer); 510 buffer_free(&buffer); 511 pthread_exit(NULL); 512 513 auth_fail: 514 buffer_put_cstring(&buffer, 515 pam_strerror(sshpam_handle, sshpam_err)); 516 /* XXX - can't do much about an error here */ 517 if (sshpam_err == PAM_ACCT_EXPIRED) 518 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, &buffer); 519 else 520 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer); 521 buffer_free(&buffer); 522 pthread_exit(NULL); 523 524 return (NULL); /* Avoid warning for non-pthread case */ 525 } 526 527 void 528 sshpam_thread_cleanup(void) 529 { 530 struct pam_ctxt *ctxt = cleanup_ctxt; 531 532 debug3("PAM: %s entering", __func__); 533 if (ctxt != NULL && ctxt->pam_thread != 0) { 534 pthread_cancel(ctxt->pam_thread); 535 pthread_join(ctxt->pam_thread, NULL); 536 close(ctxt->pam_psock); 537 close(ctxt->pam_csock); 538 memset(ctxt, 0, sizeof(*ctxt)); 539 cleanup_ctxt = NULL; 540 } 541 } 542 543 static int 544 sshpam_null_conv(int n, sshpam_const struct pam_message **msg, 545 struct pam_response **resp, void *data) 546 { 547 debug3("PAM: %s entering, %d messages", __func__, n); 548 return (PAM_CONV_ERR); 549 } 550 551 static struct pam_conv null_conv = { sshpam_null_conv, NULL }; 552 553 static int 554 sshpam_store_conv(int n, sshpam_const struct pam_message **msg, 555 struct pam_response **resp, void *data) 556 { 557 struct pam_response *reply; 558 int i; 559 size_t len; 560 561 debug3("PAM: %s called with %d messages", __func__, n); 562 *resp = NULL; 563 564 if (n <= 0 || n > PAM_MAX_NUM_MSG) 565 return (PAM_CONV_ERR); 566 567 if ((reply = calloc(n, sizeof(*reply))) == NULL) 568 return (PAM_CONV_ERR); 569 570 for (i = 0; i < n; ++i) { 571 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 572 case PAM_ERROR_MSG: 573 case PAM_TEXT_INFO: 574 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 575 buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len); 576 buffer_append(&loginmsg, "\n", 1 ); 577 reply[i].resp_retcode = PAM_SUCCESS; 578 break; 579 default: 580 goto fail; 581 } 582 } 583 *resp = reply; 584 return (PAM_SUCCESS); 585 586 fail: 587 for(i = 0; i < n; i++) { 588 free(reply[i].resp); 589 } 590 free(reply); 591 return (PAM_CONV_ERR); 592 } 593 594 static struct pam_conv store_conv = { sshpam_store_conv, NULL }; 595 596 void 597 sshpam_cleanup(void) 598 { 599 if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor())) 600 return; 601 debug("PAM: cleanup"); 602 pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv); 603 if (sshpam_session_open) { 604 debug("PAM: closing session"); 605 pam_close_session(sshpam_handle, PAM_SILENT); 606 sshpam_session_open = 0; 607 } 608 if (sshpam_cred_established) { 609 debug("PAM: deleting credentials"); 610 pam_setcred(sshpam_handle, PAM_DELETE_CRED); 611 sshpam_cred_established = 0; 612 } 613 sshpam_authenticated = 0; 614 pam_end(sshpam_handle, sshpam_err); 615 sshpam_handle = NULL; 616 } 617 618 static int 619 sshpam_init(Authctxt *authctxt) 620 { 621 extern char *__progname; 622 const char *pam_rhost, *pam_user, *user = authctxt->user; 623 const char **ptr_pam_user = &pam_user; 624 625 if (sshpam_handle != NULL) { 626 /* We already have a PAM context; check if the user matches */ 627 sshpam_err = pam_get_item(sshpam_handle, 628 PAM_USER, (sshpam_const void **)ptr_pam_user); 629 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0) 630 return (0); 631 pam_end(sshpam_handle, sshpam_err); 632 sshpam_handle = NULL; 633 } 634 debug("PAM: initializing for \"%s\"", user); 635 sshpam_err = 636 pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle); 637 sshpam_authctxt = authctxt; 638 639 if (sshpam_err != PAM_SUCCESS) { 640 pam_end(sshpam_handle, sshpam_err); 641 sshpam_handle = NULL; 642 return (-1); 643 } 644 pam_rhost = get_remote_name_or_ip(utmp_len, options.use_dns); 645 debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost); 646 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost); 647 if (sshpam_err != PAM_SUCCESS) { 648 pam_end(sshpam_handle, sshpam_err); 649 sshpam_handle = NULL; 650 return (-1); 651 } 652 #ifdef PAM_TTY_KLUDGE 653 /* 654 * Some silly PAM modules (e.g. pam_time) require a TTY to operate. 655 * sshd doesn't set the tty until too late in the auth process and 656 * may not even set one (for tty-less connections) 657 */ 658 debug("PAM: setting PAM_TTY to \"ssh\""); 659 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh"); 660 if (sshpam_err != PAM_SUCCESS) { 661 pam_end(sshpam_handle, sshpam_err); 662 sshpam_handle = NULL; 663 return (-1); 664 } 665 #endif 666 return (0); 667 } 668 669 static void * 670 sshpam_init_ctx(Authctxt *authctxt) 671 { 672 struct pam_ctxt *ctxt; 673 int socks[2]; 674 675 debug3("PAM: %s entering", __func__); 676 /* 677 * Refuse to start if we don't have PAM enabled or do_pam_account 678 * has previously failed. 679 */ 680 if (!options.use_pam || sshpam_account_status == 0) 681 return NULL; 682 683 /* Initialize PAM */ 684 if (sshpam_init(authctxt) == -1) { 685 error("PAM: initialization failed"); 686 return (NULL); 687 } 688 689 ctxt = xcalloc(1, sizeof *ctxt); 690 691 /* Start the authentication thread */ 692 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) { 693 error("PAM: failed create sockets: %s", strerror(errno)); 694 free(ctxt); 695 return (NULL); 696 } 697 ctxt->pam_psock = socks[0]; 698 ctxt->pam_csock = socks[1]; 699 if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) { 700 error("PAM: failed to start authentication thread: %s", 701 strerror(errno)); 702 close(socks[0]); 703 close(socks[1]); 704 free(ctxt); 705 return (NULL); 706 } 707 cleanup_ctxt = ctxt; 708 return (ctxt); 709 } 710 711 static int 712 sshpam_query(void *ctx, char **name, char **info, 713 u_int *num, char ***prompts, u_int **echo_on) 714 { 715 Buffer buffer; 716 struct pam_ctxt *ctxt = ctx; 717 size_t plen; 718 u_char type; 719 char *msg; 720 size_t len, mlen; 721 722 debug3("PAM: %s entering", __func__); 723 buffer_init(&buffer); 724 *name = xstrdup(""); 725 *info = xstrdup(""); 726 *prompts = xmalloc(sizeof(char *)); 727 **prompts = NULL; 728 plen = 0; 729 *echo_on = xmalloc(sizeof(u_int)); 730 while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) { 731 type = buffer_get_char(&buffer); 732 msg = buffer_get_string(&buffer, NULL); 733 mlen = strlen(msg); 734 switch (type) { 735 case PAM_PROMPT_ECHO_ON: 736 case PAM_PROMPT_ECHO_OFF: 737 *num = 1; 738 len = plen + mlen + 1; 739 **prompts = xrealloc(**prompts, 1, len); 740 strlcpy(**prompts + plen, msg, len - plen); 741 plen += mlen; 742 **echo_on = (type == PAM_PROMPT_ECHO_ON); 743 free(msg); 744 return (0); 745 case PAM_ERROR_MSG: 746 case PAM_TEXT_INFO: 747 /* accumulate messages */ 748 len = plen + mlen + 2; 749 **prompts = xrealloc(**prompts, 1, len); 750 strlcpy(**prompts + plen, msg, len - plen); 751 plen += mlen; 752 strlcat(**prompts + plen, "\n", len - plen); 753 plen++; 754 free(msg); 755 break; 756 case PAM_ACCT_EXPIRED: 757 sshpam_account_status = 0; 758 /* FALLTHROUGH */ 759 case PAM_AUTH_ERR: 760 debug3("PAM: %s", pam_strerror(sshpam_handle, type)); 761 if (**prompts != NULL && strlen(**prompts) != 0) { 762 *info = **prompts; 763 **prompts = NULL; 764 *num = 0; 765 **echo_on = 0; 766 ctxt->pam_done = -1; 767 free(msg); 768 return 0; 769 } 770 /* FALLTHROUGH */ 771 case PAM_SUCCESS: 772 if (**prompts != NULL) { 773 /* drain any accumulated messages */ 774 debug("PAM: %s", **prompts); 775 buffer_append(&loginmsg, **prompts, 776 strlen(**prompts)); 777 free(**prompts); 778 **prompts = NULL; 779 } 780 if (type == PAM_SUCCESS) { 781 if (!sshpam_authctxt->valid || 782 (sshpam_authctxt->pw->pw_uid == 0 && 783 options.permit_root_login != PERMIT_YES)) 784 fatal("Internal error: PAM auth " 785 "succeeded when it should have " 786 "failed"); 787 import_environments(&buffer); 788 *num = 0; 789 **echo_on = 0; 790 ctxt->pam_done = 1; 791 free(msg); 792 return (0); 793 } 794 error("PAM: %s for %s%.100s from %.100s", msg, 795 sshpam_authctxt->valid ? "" : "illegal user ", 796 sshpam_authctxt->user, 797 get_remote_name_or_ip(utmp_len, options.use_dns)); 798 /* FALLTHROUGH */ 799 default: 800 *num = 0; 801 **echo_on = 0; 802 free(msg); 803 ctxt->pam_done = -1; 804 return (-1); 805 } 806 } 807 return (-1); 808 } 809 810 /* XXX - see also comment in auth-chall.c:verify_response */ 811 static int 812 sshpam_respond(void *ctx, u_int num, char **resp) 813 { 814 Buffer buffer; 815 struct pam_ctxt *ctxt = ctx; 816 817 debug2("PAM: %s entering, %u responses", __func__, num); 818 switch (ctxt->pam_done) { 819 case 1: 820 sshpam_authenticated = 1; 821 return (0); 822 case 0: 823 break; 824 default: 825 return (-1); 826 } 827 if (num != 1) { 828 error("PAM: expected one response, got %u", num); 829 return (-1); 830 } 831 buffer_init(&buffer); 832 if (sshpam_authctxt->valid && 833 (sshpam_authctxt->pw->pw_uid != 0 || 834 options.permit_root_login == PERMIT_YES)) 835 buffer_put_cstring(&buffer, *resp); 836 else 837 buffer_put_cstring(&buffer, badpw); 838 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) { 839 buffer_free(&buffer); 840 return (-1); 841 } 842 buffer_free(&buffer); 843 return (1); 844 } 845 846 static void 847 sshpam_free_ctx(void *ctxtp) 848 { 849 struct pam_ctxt *ctxt = ctxtp; 850 851 debug3("PAM: %s entering", __func__); 852 sshpam_thread_cleanup(); 853 free(ctxt); 854 /* 855 * We don't call sshpam_cleanup() here because we may need the PAM 856 * handle at a later stage, e.g. when setting up a session. It's 857 * still on the cleanup list, so pam_end() *will* be called before 858 * the server process terminates. 859 */ 860 } 861 862 KbdintDevice sshpam_device = { 863 "pam", 864 sshpam_init_ctx, 865 sshpam_query, 866 sshpam_respond, 867 sshpam_free_ctx 868 }; 869 870 KbdintDevice mm_sshpam_device = { 871 "pam", 872 mm_sshpam_init_ctx, 873 mm_sshpam_query, 874 mm_sshpam_respond, 875 mm_sshpam_free_ctx 876 }; 877 878 /* 879 * This replaces auth-pam.c 880 */ 881 void 882 start_pam(Authctxt *authctxt) 883 { 884 if (!options.use_pam) 885 fatal("PAM: initialisation requested when UsePAM=no"); 886 887 if (sshpam_init(authctxt) == -1) 888 fatal("PAM: initialisation failed"); 889 } 890 891 void 892 finish_pam(void) 893 { 894 sshpam_cleanup(); 895 } 896 897 u_int 898 do_pam_account(void) 899 { 900 debug("%s: called", __func__); 901 if (sshpam_account_status != -1) 902 return (sshpam_account_status); 903 904 sshpam_err = pam_acct_mgmt(sshpam_handle, 0); 905 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err, 906 pam_strerror(sshpam_handle, sshpam_err)); 907 908 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) { 909 sshpam_account_status = 0; 910 return (sshpam_account_status); 911 } 912 913 if (sshpam_err == PAM_NEW_AUTHTOK_REQD) 914 sshpam_password_change_required(1); 915 916 sshpam_account_status = 1; 917 return (sshpam_account_status); 918 } 919 920 void 921 do_pam_set_tty(const char *tty) 922 { 923 if (tty != NULL) { 924 debug("PAM: setting PAM_TTY to \"%s\"", tty); 925 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty); 926 if (sshpam_err != PAM_SUCCESS) 927 fatal("PAM: failed to set PAM_TTY: %s", 928 pam_strerror(sshpam_handle, sshpam_err)); 929 } 930 } 931 932 void 933 do_pam_setcred(int init) 934 { 935 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 936 (const void *)&store_conv); 937 if (sshpam_err != PAM_SUCCESS) 938 fatal("PAM: failed to set PAM_CONV: %s", 939 pam_strerror(sshpam_handle, sshpam_err)); 940 if (init) { 941 debug("PAM: establishing credentials"); 942 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED); 943 } else { 944 debug("PAM: reinitializing credentials"); 945 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED); 946 } 947 if (sshpam_err == PAM_SUCCESS) { 948 sshpam_cred_established = 1; 949 return; 950 } 951 if (sshpam_authenticated) 952 fatal("PAM: pam_setcred(): %s", 953 pam_strerror(sshpam_handle, sshpam_err)); 954 else 955 debug("PAM: pam_setcred(): %s", 956 pam_strerror(sshpam_handle, sshpam_err)); 957 } 958 959 static int 960 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg, 961 struct pam_response **resp, void *data) 962 { 963 char input[PAM_MAX_MSG_SIZE]; 964 struct pam_response *reply; 965 int i; 966 967 debug3("PAM: %s called with %d messages", __func__, n); 968 969 *resp = NULL; 970 971 if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO)) 972 return (PAM_CONV_ERR); 973 974 if ((reply = calloc(n, sizeof(*reply))) == NULL) 975 return (PAM_CONV_ERR); 976 977 for (i = 0; i < n; ++i) { 978 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 979 case PAM_PROMPT_ECHO_OFF: 980 reply[i].resp = 981 read_passphrase(PAM_MSG_MEMBER(msg, i, msg), 982 RP_ALLOW_STDIN); 983 reply[i].resp_retcode = PAM_SUCCESS; 984 break; 985 case PAM_PROMPT_ECHO_ON: 986 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 987 if (fgets(input, sizeof input, stdin) == NULL) 988 input[0] = '\0'; 989 if ((reply[i].resp = strdup(input)) == NULL) 990 goto fail; 991 reply[i].resp_retcode = PAM_SUCCESS; 992 break; 993 case PAM_ERROR_MSG: 994 case PAM_TEXT_INFO: 995 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 996 reply[i].resp_retcode = PAM_SUCCESS; 997 break; 998 default: 999 goto fail; 1000 } 1001 } 1002 *resp = reply; 1003 return (PAM_SUCCESS); 1004 1005 fail: 1006 for(i = 0; i < n; i++) { 1007 free(reply[i].resp); 1008 } 1009 free(reply); 1010 return (PAM_CONV_ERR); 1011 } 1012 1013 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL }; 1014 1015 /* 1016 * XXX this should be done in the authentication phase, but ssh1 doesn't 1017 * support that 1018 */ 1019 void 1020 do_pam_chauthtok(void) 1021 { 1022 if (use_privsep) 1023 fatal("Password expired (unable to change with privsep)"); 1024 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1025 (const void *)&tty_conv); 1026 if (sshpam_err != PAM_SUCCESS) 1027 fatal("PAM: failed to set PAM_CONV: %s", 1028 pam_strerror(sshpam_handle, sshpam_err)); 1029 debug("PAM: changing password"); 1030 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK); 1031 if (sshpam_err != PAM_SUCCESS) 1032 fatal("PAM: pam_chauthtok(): %s", 1033 pam_strerror(sshpam_handle, sshpam_err)); 1034 } 1035 1036 void 1037 do_pam_session(void) 1038 { 1039 debug3("PAM: opening session"); 1040 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1041 (const void *)&store_conv); 1042 if (sshpam_err != PAM_SUCCESS) 1043 fatal("PAM: failed to set PAM_CONV: %s", 1044 pam_strerror(sshpam_handle, sshpam_err)); 1045 sshpam_err = pam_open_session(sshpam_handle, 0); 1046 if (sshpam_err == PAM_SUCCESS) 1047 sshpam_session_open = 1; 1048 else { 1049 sshpam_session_open = 0; 1050 disable_forwarding(); 1051 error("PAM: pam_open_session(): %s", 1052 pam_strerror(sshpam_handle, sshpam_err)); 1053 } 1054 1055 } 1056 1057 int 1058 is_pam_session_open(void) 1059 { 1060 return sshpam_session_open; 1061 } 1062 1063 /* 1064 * Set a PAM environment string. We need to do this so that the session 1065 * modules can handle things like Kerberos/GSI credentials that appear 1066 * during the ssh authentication process. 1067 */ 1068 int 1069 do_pam_putenv(char *name, char *value) 1070 { 1071 int ret = 1; 1072 #ifdef HAVE_PAM_PUTENV 1073 char *compound; 1074 size_t len; 1075 1076 len = strlen(name) + strlen(value) + 2; 1077 compound = xmalloc(len); 1078 1079 snprintf(compound, len, "%s=%s", name, value); 1080 ret = pam_putenv(sshpam_handle, compound); 1081 free(compound); 1082 #endif 1083 1084 return (ret); 1085 } 1086 1087 char ** 1088 fetch_pam_child_environment(void) 1089 { 1090 return sshpam_env; 1091 } 1092 1093 char ** 1094 fetch_pam_environment(void) 1095 { 1096 return (pam_getenvlist(sshpam_handle)); 1097 } 1098 1099 void 1100 free_pam_environment(char **env) 1101 { 1102 char **envp; 1103 1104 if (env == NULL) 1105 return; 1106 1107 for (envp = env; *envp; envp++) 1108 free(*envp); 1109 free(env); 1110 } 1111 1112 /* 1113 * "Blind" conversation function for password authentication. Assumes that 1114 * echo-off prompts are for the password and stores messages for later 1115 * display. 1116 */ 1117 static int 1118 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg, 1119 struct pam_response **resp, void *data) 1120 { 1121 struct pam_response *reply; 1122 int i; 1123 size_t len; 1124 1125 debug3("PAM: %s called with %d messages", __func__, n); 1126 1127 *resp = NULL; 1128 1129 if (n <= 0 || n > PAM_MAX_NUM_MSG) 1130 return (PAM_CONV_ERR); 1131 1132 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1133 return (PAM_CONV_ERR); 1134 1135 for (i = 0; i < n; ++i) { 1136 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1137 case PAM_PROMPT_ECHO_OFF: 1138 if (sshpam_password == NULL) 1139 goto fail; 1140 if ((reply[i].resp = strdup(sshpam_password)) == NULL) 1141 goto fail; 1142 reply[i].resp_retcode = PAM_SUCCESS; 1143 break; 1144 case PAM_ERROR_MSG: 1145 case PAM_TEXT_INFO: 1146 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 1147 if (len > 0) { 1148 buffer_append(&loginmsg, 1149 PAM_MSG_MEMBER(msg, i, msg), len); 1150 buffer_append(&loginmsg, "\n", 1); 1151 } 1152 if ((reply[i].resp = strdup("")) == NULL) 1153 goto fail; 1154 reply[i].resp_retcode = PAM_SUCCESS; 1155 break; 1156 default: 1157 goto fail; 1158 } 1159 } 1160 *resp = reply; 1161 return (PAM_SUCCESS); 1162 1163 fail: 1164 for(i = 0; i < n; i++) { 1165 free(reply[i].resp); 1166 } 1167 free(reply); 1168 return (PAM_CONV_ERR); 1169 } 1170 1171 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL }; 1172 1173 /* 1174 * Attempt password authentication via PAM 1175 */ 1176 int 1177 sshpam_auth_passwd(Authctxt *authctxt, const char *password) 1178 { 1179 int flags = (options.permit_empty_passwd == 0 ? 1180 PAM_DISALLOW_NULL_AUTHTOK : 0); 1181 1182 if (!options.use_pam || sshpam_handle == NULL) 1183 fatal("PAM: %s called when PAM disabled or failed to " 1184 "initialise.", __func__); 1185 1186 sshpam_password = password; 1187 sshpam_authctxt = authctxt; 1188 1189 /* 1190 * If the user logging in is invalid, or is root but is not permitted 1191 * by PermitRootLogin, use an invalid password to prevent leaking 1192 * information via timing (eg if the PAM config has a delay on fail). 1193 */ 1194 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 && 1195 options.permit_root_login != PERMIT_YES)) 1196 sshpam_password = badpw; 1197 1198 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1199 (const void *)&passwd_conv); 1200 if (sshpam_err != PAM_SUCCESS) 1201 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__, 1202 pam_strerror(sshpam_handle, sshpam_err)); 1203 1204 sshpam_err = pam_authenticate(sshpam_handle, flags); 1205 sshpam_password = NULL; 1206 if (sshpam_err == PAM_SUCCESS && authctxt->valid) { 1207 debug("PAM: password authentication accepted for %.100s", 1208 authctxt->user); 1209 return 1; 1210 } else { 1211 debug("PAM: password authentication failed for %.100s: %s", 1212 authctxt->valid ? authctxt->user : "an illegal user", 1213 pam_strerror(sshpam_handle, sshpam_err)); 1214 return 0; 1215 } 1216 } 1217 #endif /* USE_PAM */ 1218