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" 102 103 extern ServerOptions options; 104 extern Buffer loginmsg; 105 extern int compat20; 106 extern 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 */ 125 typedef pthread_t sp_pthread_t; 126 #else 127 typedef pid_t sp_pthread_t; 128 #endif 129 130 struct pam_ctxt { 131 sp_pthread_t pam_thread; 132 int pam_psock; 133 int pam_csock; 134 int pam_done; 135 }; 136 137 static void sshpam_free_ctx(void *); 138 static struct pam_ctxt *cleanup_ctxt; 139 140 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 141 /* 142 * Simulate threads with processes. 143 */ 144 145 static int sshpam_thread_status = -1; 146 static mysig_t sshpam_oldsig; 147 148 static void 149 sshpam_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 */ 172 static void 173 pthread_exit(void *value) 174 { 175 _exit(0); 176 } 177 178 /* ARGSUSED */ 179 static int 180 pthread_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 } 204 205 static int 206 pthread_cancel(sp_pthread_t thread) 207 { 208 signal(SIGCHLD, sshpam_oldsig); 209 return (kill(thread, SIGTERM)); 210 } 211 212 /* ARGSUSED */ 213 static int 214 pthread_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 225 226 227 static pam_handle_t *sshpam_handle = NULL; 228 static int sshpam_err = 0; 229 static int sshpam_authenticated = 0; 230 static int sshpam_session_open = 0; 231 static int sshpam_cred_established = 0; 232 static int sshpam_account_status = -1; 233 static char **sshpam_env = NULL; 234 static Authctxt *sshpam_authctxt = NULL; 235 static const char *sshpam_password = NULL; 236 static char badpw[] = "\b\n\r\177INCORRECT"; 237 238 /* Some PAM implementations don't implement this */ 239 #ifndef HAVE_PAM_GETENVLIST 240 static char ** 241 pam_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 260 static int 261 sshpam_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 276 277 void 278 sshpam_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 */ 296 static void 297 import_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 */ 342 static int 343 sshpam_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 */ 427 static void * 428 sshpam_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 } 530 531 void 532 sshpam_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 } 546 547 static int 548 sshpam_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 } 554 555 static struct pam_conv null_conv = { sshpam_null_conv, NULL }; 556 557 static int 558 sshpam_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 } 597 598 static struct pam_conv store_conv = { sshpam_store_conv, NULL }; 599 600 void 601 sshpam_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 } 621 622 static int 623 sshpam_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 } 672 673 static void * 674 sshpam_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 } 714 715 static int 716 sshpam_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_AUTH_FAIL); 799 error("PAM: %s for %s%.100s from %.100s", msg, 800 sshpam_authctxt->valid ? "" : "illegal user ", 801 sshpam_authctxt->user, 802 get_remote_name_or_ip(utmp_len, options.use_dns)); 803 /* FALLTHROUGH */ 804 default: 805 *num = 0; 806 **echo_on = 0; 807 free(msg); 808 ctxt->pam_done = -1; 809 return (-1); 810 } 811 } 812 return (-1); 813 } 814 815 /* XXX - see also comment in auth-chall.c:verify_response */ 816 static int 817 sshpam_respond(void *ctx, u_int num, char **resp) 818 { 819 Buffer buffer; 820 struct pam_ctxt *ctxt = ctx; 821 822 debug2("PAM: %s entering, %u responses", __func__, num); 823 switch (ctxt->pam_done) { 824 case 1: 825 sshpam_authenticated = 1; 826 return (0); 827 case 0: 828 break; 829 default: 830 return (-1); 831 } 832 if (num != 1) { 833 error("PAM: expected one response, got %u", num); 834 return (-1); 835 } 836 buffer_init(&buffer); 837 if (sshpam_authctxt->valid && 838 (sshpam_authctxt->pw->pw_uid != 0 || 839 options.permit_root_login == PERMIT_YES)) 840 buffer_put_cstring(&buffer, *resp); 841 else 842 buffer_put_cstring(&buffer, badpw); 843 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) { 844 buffer_free(&buffer); 845 return (-1); 846 } 847 buffer_free(&buffer); 848 return (1); 849 } 850 851 static void 852 sshpam_free_ctx(void *ctxtp) 853 { 854 struct pam_ctxt *ctxt = ctxtp; 855 856 debug3("PAM: %s entering", __func__); 857 sshpam_thread_cleanup(); 858 free(ctxt); 859 /* 860 * We don't call sshpam_cleanup() here because we may need the PAM 861 * handle at a later stage, e.g. when setting up a session. It's 862 * still on the cleanup list, so pam_end() *will* be called before 863 * the server process terminates. 864 */ 865 } 866 867 KbdintDevice sshpam_device = { 868 "pam", 869 sshpam_init_ctx, 870 sshpam_query, 871 sshpam_respond, 872 sshpam_free_ctx 873 }; 874 875 KbdintDevice mm_sshpam_device = { 876 "pam", 877 mm_sshpam_init_ctx, 878 mm_sshpam_query, 879 mm_sshpam_respond, 880 mm_sshpam_free_ctx 881 }; 882 883 /* 884 * This replaces auth-pam.c 885 */ 886 void 887 start_pam(Authctxt *authctxt) 888 { 889 if (!options.use_pam) 890 fatal("PAM: initialisation requested when UsePAM=no"); 891 892 if (sshpam_init(authctxt) == -1) 893 fatal("PAM: initialisation failed"); 894 } 895 896 void 897 finish_pam(void) 898 { 899 sshpam_cleanup(); 900 } 901 902 u_int 903 do_pam_account(void) 904 { 905 debug("%s: called", __func__); 906 if (sshpam_account_status != -1) 907 return (sshpam_account_status); 908 909 sshpam_err = pam_acct_mgmt(sshpam_handle, 0); 910 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err, 911 pam_strerror(sshpam_handle, sshpam_err)); 912 913 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) { 914 sshpam_account_status = 0; 915 return (sshpam_account_status); 916 } 917 918 if (sshpam_err == PAM_NEW_AUTHTOK_REQD) 919 sshpam_password_change_required(1); 920 921 sshpam_account_status = 1; 922 return (sshpam_account_status); 923 } 924 925 void 926 do_pam_set_tty(const char *tty) 927 { 928 if (tty != NULL) { 929 debug("PAM: setting PAM_TTY to \"%s\"", tty); 930 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, tty); 931 if (sshpam_err != PAM_SUCCESS) 932 fatal("PAM: failed to set PAM_TTY: %s", 933 pam_strerror(sshpam_handle, sshpam_err)); 934 } 935 } 936 937 void 938 do_pam_setcred(int init) 939 { 940 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 941 (const void *)&store_conv); 942 if (sshpam_err != PAM_SUCCESS) 943 fatal("PAM: failed to set PAM_CONV: %s", 944 pam_strerror(sshpam_handle, sshpam_err)); 945 if (init) { 946 debug("PAM: establishing credentials"); 947 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED); 948 } else { 949 debug("PAM: reinitializing credentials"); 950 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED); 951 } 952 if (sshpam_err == PAM_SUCCESS) { 953 sshpam_cred_established = 1; 954 return; 955 } 956 if (sshpam_authenticated) 957 fatal("PAM: pam_setcred(): %s", 958 pam_strerror(sshpam_handle, sshpam_err)); 959 else 960 debug("PAM: pam_setcred(): %s", 961 pam_strerror(sshpam_handle, sshpam_err)); 962 } 963 964 static int 965 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg, 966 struct pam_response **resp, void *data) 967 { 968 char input[PAM_MAX_MSG_SIZE]; 969 struct pam_response *reply; 970 int i; 971 972 debug3("PAM: %s called with %d messages", __func__, n); 973 974 *resp = NULL; 975 976 if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO)) 977 return (PAM_CONV_ERR); 978 979 if ((reply = calloc(n, sizeof(*reply))) == NULL) 980 return (PAM_CONV_ERR); 981 982 for (i = 0; i < n; ++i) { 983 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 984 case PAM_PROMPT_ECHO_OFF: 985 reply[i].resp = 986 read_passphrase(PAM_MSG_MEMBER(msg, i, msg), 987 RP_ALLOW_STDIN); 988 reply[i].resp_retcode = PAM_SUCCESS; 989 break; 990 case PAM_PROMPT_ECHO_ON: 991 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 992 if (fgets(input, sizeof input, stdin) == NULL) 993 input[0] = '\0'; 994 if ((reply[i].resp = strdup(input)) == NULL) 995 goto fail; 996 reply[i].resp_retcode = PAM_SUCCESS; 997 break; 998 case PAM_ERROR_MSG: 999 case PAM_TEXT_INFO: 1000 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1001 reply[i].resp_retcode = PAM_SUCCESS; 1002 break; 1003 default: 1004 goto fail; 1005 } 1006 } 1007 *resp = reply; 1008 return (PAM_SUCCESS); 1009 1010 fail: 1011 for(i = 0; i < n; i++) { 1012 free(reply[i].resp); 1013 } 1014 free(reply); 1015 return (PAM_CONV_ERR); 1016 } 1017 1018 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL }; 1019 1020 /* 1021 * XXX this should be done in the authentication phase, but ssh1 doesn't 1022 * support that 1023 */ 1024 void 1025 do_pam_chauthtok(void) 1026 { 1027 if (use_privsep) 1028 fatal("Password expired (unable to change with privsep)"); 1029 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1030 (const void *)&tty_conv); 1031 if (sshpam_err != PAM_SUCCESS) 1032 fatal("PAM: failed to set PAM_CONV: %s", 1033 pam_strerror(sshpam_handle, sshpam_err)); 1034 debug("PAM: changing password"); 1035 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK); 1036 if (sshpam_err != PAM_SUCCESS) 1037 fatal("PAM: pam_chauthtok(): %s", 1038 pam_strerror(sshpam_handle, sshpam_err)); 1039 } 1040 1041 void 1042 do_pam_session(void) 1043 { 1044 debug3("PAM: opening session"); 1045 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1046 (const void *)&store_conv); 1047 if (sshpam_err != PAM_SUCCESS) 1048 fatal("PAM: failed to set PAM_CONV: %s", 1049 pam_strerror(sshpam_handle, sshpam_err)); 1050 sshpam_err = pam_open_session(sshpam_handle, 0); 1051 if (sshpam_err == PAM_SUCCESS) 1052 sshpam_session_open = 1; 1053 else { 1054 sshpam_session_open = 0; 1055 disable_forwarding(); 1056 error("PAM: pam_open_session(): %s", 1057 pam_strerror(sshpam_handle, sshpam_err)); 1058 } 1059 1060 } 1061 1062 int 1063 is_pam_session_open(void) 1064 { 1065 return sshpam_session_open; 1066 } 1067 1068 /* 1069 * Set a PAM environment string. We need to do this so that the session 1070 * modules can handle things like Kerberos/GSI credentials that appear 1071 * during the ssh authentication process. 1072 */ 1073 int 1074 do_pam_putenv(char *name, char *value) 1075 { 1076 int ret = 1; 1077 #ifdef HAVE_PAM_PUTENV 1078 char *compound; 1079 size_t len; 1080 1081 len = strlen(name) + strlen(value) + 2; 1082 compound = xmalloc(len); 1083 1084 snprintf(compound, len, "%s=%s", name, value); 1085 ret = pam_putenv(sshpam_handle, compound); 1086 free(compound); 1087 #endif 1088 1089 return (ret); 1090 } 1091 1092 char ** 1093 fetch_pam_child_environment(void) 1094 { 1095 return sshpam_env; 1096 } 1097 1098 char ** 1099 fetch_pam_environment(void) 1100 { 1101 return (pam_getenvlist(sshpam_handle)); 1102 } 1103 1104 void 1105 free_pam_environment(char **env) 1106 { 1107 char **envp; 1108 1109 if (env == NULL) 1110 return; 1111 1112 for (envp = env; *envp; envp++) 1113 free(*envp); 1114 free(env); 1115 } 1116 1117 /* 1118 * "Blind" conversation function for password authentication. Assumes that 1119 * echo-off prompts are for the password and stores messages for later 1120 * display. 1121 */ 1122 static int 1123 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg, 1124 struct pam_response **resp, void *data) 1125 { 1126 struct pam_response *reply; 1127 int i; 1128 size_t len; 1129 1130 debug3("PAM: %s called with %d messages", __func__, n); 1131 1132 *resp = NULL; 1133 1134 if (n <= 0 || n > PAM_MAX_NUM_MSG) 1135 return (PAM_CONV_ERR); 1136 1137 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1138 return (PAM_CONV_ERR); 1139 1140 for (i = 0; i < n; ++i) { 1141 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1142 case PAM_PROMPT_ECHO_OFF: 1143 if (sshpam_password == NULL) 1144 goto fail; 1145 if ((reply[i].resp = strdup(sshpam_password)) == NULL) 1146 goto fail; 1147 reply[i].resp_retcode = PAM_SUCCESS; 1148 break; 1149 case PAM_ERROR_MSG: 1150 case PAM_TEXT_INFO: 1151 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 1152 if (len > 0) { 1153 buffer_append(&loginmsg, 1154 PAM_MSG_MEMBER(msg, i, msg), len); 1155 buffer_append(&loginmsg, "\n", 1); 1156 } 1157 if ((reply[i].resp = strdup("")) == NULL) 1158 goto fail; 1159 reply[i].resp_retcode = PAM_SUCCESS; 1160 break; 1161 default: 1162 goto fail; 1163 } 1164 } 1165 *resp = reply; 1166 return (PAM_SUCCESS); 1167 1168 fail: 1169 for(i = 0; i < n; i++) { 1170 free(reply[i].resp); 1171 } 1172 free(reply); 1173 return (PAM_CONV_ERR); 1174 } 1175 1176 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL }; 1177 1178 /* 1179 * Attempt password authentication via PAM 1180 */ 1181 int 1182 sshpam_auth_passwd(Authctxt *authctxt, const char *password) 1183 { 1184 int flags = (options.permit_empty_passwd == 0 ? 1185 PAM_DISALLOW_NULL_AUTHTOK : 0); 1186 1187 if (!options.use_pam || sshpam_handle == NULL) 1188 fatal("PAM: %s called when PAM disabled or failed to " 1189 "initialise.", __func__); 1190 1191 sshpam_password = password; 1192 sshpam_authctxt = authctxt; 1193 1194 /* 1195 * If the user logging in is invalid, or is root but is not permitted 1196 * by PermitRootLogin, use an invalid password to prevent leaking 1197 * information via timing (eg if the PAM config has a delay on fail). 1198 */ 1199 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 && 1200 options.permit_root_login != PERMIT_YES)) 1201 sshpam_password = badpw; 1202 1203 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1204 (const void *)&passwd_conv); 1205 if (sshpam_err != PAM_SUCCESS) 1206 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__, 1207 pam_strerror(sshpam_handle, sshpam_err)); 1208 1209 sshpam_err = pam_authenticate(sshpam_handle, flags); 1210 sshpam_password = NULL; 1211 if (sshpam_err == PAM_SUCCESS && authctxt->valid) { 1212 debug("PAM: password authentication accepted for %.100s", 1213 authctxt->user); 1214 return 1; 1215 } else { 1216 debug("PAM: password authentication failed for %.100s: %s", 1217 authctxt->valid ? authctxt->user : "an illegal user", 1218 pam_strerror(sshpam_handle, sshpam_err)); 1219 return 0; 1220 } 1221 } 1222 #endif /* USE_PAM */ 1223