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