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 #if !defined(SSHD_PAM_SERVICE) 70 extern char *__progname; 71 # define SSHD_PAM_SERVICE __progname 72 #endif 73 74 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */ 75 #ifdef PAM_SUN_CODEBASE 76 # define sshpam_const /* Solaris, HP-UX, SunOS */ 77 #else 78 # define sshpam_const const /* LinuxPAM, OpenPAM, AIX */ 79 #endif 80 81 /* Ambiguity in spec: is it an array of pointers or a pointer to an array? */ 82 #ifdef PAM_SUN_CODEBASE 83 # define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member) 84 #else 85 # define PAM_MSG_MEMBER(msg, n, member) ((msg)[(n)]->member) 86 #endif 87 88 #include "xmalloc.h" 89 #include "buffer.h" 90 #include "key.h" 91 #include "hostfile.h" 92 #include "auth.h" 93 #include "auth-pam.h" 94 #include "canohost.h" 95 #include "log.h" 96 #include "msg.h" 97 #include "packet.h" 98 #include "misc.h" 99 #include "servconf.h" 100 #include "ssh2.h" 101 #include "auth-options.h" 102 #ifdef GSSAPI 103 #include "ssh-gss.h" 104 #endif 105 #include "monitor_wrap.h" 106 #include "blacklist_client.h" 107 108 extern ServerOptions options; 109 extern Buffer loginmsg; 110 extern u_int utmp_len; 111 112 /* so we don't silently change behaviour */ 113 #ifdef USE_POSIX_THREADS 114 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK" 115 #endif 116 117 /* 118 * Formerly known as USE_POSIX_THREADS, using this is completely unsupported 119 * and generally a bad idea. Use at own risk and do not expect support if 120 * this breaks. 121 */ 122 #ifdef UNSUPPORTED_POSIX_THREADS_HACK 123 #include <pthread.h> 124 /* 125 * Avoid namespace clash when *not* using pthreads for systems *with* 126 * pthreads, which unconditionally define pthread_t via sys/types.h 127 * (e.g. Linux) 128 */ 129 typedef pthread_t sp_pthread_t; 130 #else 131 typedef pid_t sp_pthread_t; 132 #endif 133 134 struct pam_ctxt { 135 sp_pthread_t pam_thread; 136 int pam_psock; 137 int pam_csock; 138 int pam_done; 139 }; 140 141 static void sshpam_free_ctx(void *); 142 static struct pam_ctxt *cleanup_ctxt; 143 144 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 145 /* 146 * Simulate threads with processes. 147 */ 148 149 static int sshpam_thread_status = -1; 150 static mysig_t sshpam_oldsig; 151 152 static void 153 sshpam_sigchld_handler(int sig) 154 { 155 signal(SIGCHLD, SIG_DFL); 156 if (cleanup_ctxt == NULL) 157 return; /* handler called after PAM cleanup, shouldn't happen */ 158 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG) 159 <= 0) { 160 /* PAM thread has not exitted, privsep slave must have */ 161 kill(cleanup_ctxt->pam_thread, SIGTERM); 162 while (waitpid(cleanup_ctxt->pam_thread, 163 &sshpam_thread_status, 0) == -1) { 164 if (errno == EINTR) 165 continue; 166 return; 167 } 168 } 169 if (WIFSIGNALED(sshpam_thread_status) && 170 WTERMSIG(sshpam_thread_status) == SIGTERM) 171 return; /* terminated by pthread_cancel */ 172 if (!WIFEXITED(sshpam_thread_status)) 173 sigdie("PAM: authentication thread exited unexpectedly"); 174 if (WEXITSTATUS(sshpam_thread_status) != 0) 175 sigdie("PAM: authentication thread exited uncleanly"); 176 } 177 178 /* ARGSUSED */ 179 static void 180 pthread_exit(void *value) 181 { 182 _exit(0); 183 } 184 185 /* ARGSUSED */ 186 static int 187 pthread_create(sp_pthread_t *thread, const void *attr, 188 void *(*thread_start)(void *), void *arg) 189 { 190 pid_t pid; 191 struct pam_ctxt *ctx = arg; 192 193 sshpam_thread_status = -1; 194 switch ((pid = fork())) { 195 case -1: 196 error("fork(): %s", strerror(errno)); 197 return (-1); 198 case 0: 199 close(ctx->pam_psock); 200 ctx->pam_psock = -1; 201 thread_start(arg); 202 _exit(1); 203 default: 204 *thread = pid; 205 close(ctx->pam_csock); 206 ctx->pam_csock = -1; 207 sshpam_oldsig = signal(SIGCHLD, sshpam_sigchld_handler); 208 return (0); 209 } 210 } 211 212 static int 213 pthread_cancel(sp_pthread_t thread) 214 { 215 signal(SIGCHLD, sshpam_oldsig); 216 return (kill(thread, SIGTERM)); 217 } 218 219 /* ARGSUSED */ 220 static int 221 pthread_join(sp_pthread_t thread, void **value) 222 { 223 int status; 224 225 if (sshpam_thread_status != -1) 226 return (sshpam_thread_status); 227 signal(SIGCHLD, sshpam_oldsig); 228 while (waitpid(thread, &status, 0) == -1) { 229 if (errno == EINTR) 230 continue; 231 fatal("%s: waitpid: %s", __func__, strerror(errno)); 232 } 233 return (status); 234 } 235 #endif 236 237 238 static pam_handle_t *sshpam_handle = NULL; 239 static int sshpam_err = 0; 240 static int sshpam_authenticated = 0; 241 static int sshpam_session_open = 0; 242 static int sshpam_cred_established = 0; 243 static int sshpam_account_status = -1; 244 static int sshpam_maxtries_reached = 0; 245 static char **sshpam_env = NULL; 246 static Authctxt *sshpam_authctxt = NULL; 247 static const char *sshpam_password = NULL; 248 249 /* Some PAM implementations don't implement this */ 250 #ifndef HAVE_PAM_GETENVLIST 251 static char ** 252 pam_getenvlist(pam_handle_t *pamh) 253 { 254 /* 255 * XXX - If necessary, we can still support envrionment passing 256 * for platforms without pam_getenvlist by searching for known 257 * env vars (e.g. KRB5CCNAME) from the PAM environment. 258 */ 259 return NULL; 260 } 261 #endif 262 263 /* 264 * Some platforms, notably Solaris, do not enforce password complexity 265 * rules during pam_chauthtok() if the real uid of the calling process 266 * is 0, on the assumption that it's being called by "passwd" run by root. 267 * This wraps pam_chauthtok and sets/restore the real uid so PAM will do 268 * the right thing. 269 */ 270 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID 271 static int 272 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags) 273 { 274 int result; 275 276 if (sshpam_authctxt == NULL) 277 fatal("PAM: sshpam_authctxt not initialized"); 278 if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1) 279 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 280 result = pam_chauthtok(pamh, flags); 281 if (setreuid(0, -1) == -1) 282 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 283 return result; 284 } 285 # define pam_chauthtok(a,b) (sshpam_chauthtok_ruid((a), (b))) 286 #endif 287 288 void 289 sshpam_password_change_required(int reqd) 290 { 291 extern struct sshauthopt *auth_opts; 292 static int saved_port, saved_agent, saved_x11; 293 294 debug3("%s %d", __func__, reqd); 295 if (sshpam_authctxt == NULL) 296 fatal("%s: PAM authctxt not initialized", __func__); 297 sshpam_authctxt->force_pwchange = reqd; 298 if (reqd) { 299 saved_port = auth_opts->permit_port_forwarding_flag; 300 saved_agent = auth_opts->permit_agent_forwarding_flag; 301 saved_x11 = auth_opts->permit_x11_forwarding_flag; 302 auth_opts->permit_port_forwarding_flag = 0; 303 auth_opts->permit_agent_forwarding_flag = 0; 304 auth_opts->permit_x11_forwarding_flag = 0; 305 } else { 306 if (saved_port) 307 auth_opts->permit_port_forwarding_flag = saved_port; 308 if (saved_agent) 309 auth_opts->permit_agent_forwarding_flag = saved_agent; 310 if (saved_x11) 311 auth_opts->permit_x11_forwarding_flag = saved_x11; 312 } 313 } 314 315 /* Import regular and PAM environment from subprocess */ 316 static void 317 import_environments(Buffer *b) 318 { 319 char *env; 320 u_int i, num_env; 321 int err; 322 323 debug3("PAM: %s entering", __func__); 324 325 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 326 /* Import variables set by do_pam_account */ 327 sshpam_account_status = buffer_get_int(b); 328 sshpam_password_change_required(buffer_get_int(b)); 329 330 /* Import environment from subprocess */ 331 num_env = buffer_get_int(b); 332 if (num_env > 1024) 333 fatal("%s: received %u environment variables, expected <= 1024", 334 __func__, num_env); 335 sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env)); 336 debug3("PAM: num env strings %d", num_env); 337 for(i = 0; i < num_env; i++) 338 sshpam_env[i] = buffer_get_string(b, NULL); 339 340 sshpam_env[num_env] = NULL; 341 342 /* Import PAM environment from subprocess */ 343 num_env = buffer_get_int(b); 344 debug("PAM: num PAM env strings %d", num_env); 345 for(i = 0; i < num_env; i++) { 346 env = buffer_get_string(b, NULL); 347 348 #ifdef HAVE_PAM_PUTENV 349 /* Errors are not fatal here */ 350 if ((err = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) { 351 error("PAM: pam_putenv: %s", 352 pam_strerror(sshpam_handle, sshpam_err)); 353 } 354 #endif 355 } 356 #endif 357 } 358 359 /* 360 * Conversation function for authentication thread. 361 */ 362 static int 363 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg, 364 struct pam_response **resp, void *data) 365 { 366 Buffer buffer; 367 struct pam_ctxt *ctxt; 368 struct pam_response *reply; 369 int i; 370 371 debug3("PAM: %s entering, %d messages", __func__, n); 372 *resp = NULL; 373 374 if (data == NULL) { 375 error("PAM: conversation function passed a null context"); 376 return (PAM_CONV_ERR); 377 } 378 ctxt = data; 379 if (n <= 0 || n > PAM_MAX_NUM_MSG) 380 return (PAM_CONV_ERR); 381 382 if ((reply = calloc(n, sizeof(*reply))) == NULL) 383 return (PAM_CONV_ERR); 384 385 buffer_init(&buffer); 386 for (i = 0; i < n; ++i) { 387 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 388 case PAM_PROMPT_ECHO_OFF: 389 case PAM_PROMPT_ECHO_ON: 390 buffer_put_cstring(&buffer, 391 PAM_MSG_MEMBER(msg, i, msg)); 392 if (ssh_msg_send(ctxt->pam_csock, 393 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1) 394 goto fail; 395 if (ssh_msg_recv(ctxt->pam_csock, &buffer) == -1) 396 goto fail; 397 if (buffer_get_char(&buffer) != PAM_AUTHTOK) 398 goto fail; 399 reply[i].resp = buffer_get_string(&buffer, NULL); 400 break; 401 case PAM_ERROR_MSG: 402 case PAM_TEXT_INFO: 403 buffer_put_cstring(&buffer, 404 PAM_MSG_MEMBER(msg, i, msg)); 405 if (ssh_msg_send(ctxt->pam_csock, 406 PAM_MSG_MEMBER(msg, i, msg_style), &buffer) == -1) 407 goto fail; 408 break; 409 default: 410 goto fail; 411 } 412 buffer_clear(&buffer); 413 } 414 buffer_free(&buffer); 415 *resp = reply; 416 return (PAM_SUCCESS); 417 418 fail: 419 for(i = 0; i < n; i++) { 420 free(reply[i].resp); 421 } 422 free(reply); 423 buffer_free(&buffer); 424 return (PAM_CONV_ERR); 425 } 426 427 /* 428 * Authentication thread. 429 */ 430 static void * 431 sshpam_thread(void *ctxtp) 432 { 433 struct pam_ctxt *ctxt = ctxtp; 434 Buffer buffer; 435 struct pam_conv sshpam_conv; 436 int flags = (options.permit_empty_passwd == 0 ? 437 PAM_DISALLOW_NULL_AUTHTOK : 0); 438 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 439 extern char **environ; 440 char **env_from_pam; 441 u_int i; 442 const char *pam_user; 443 const char **ptr_pam_user = &pam_user; 444 char *tz = getenv("TZ"); 445 446 sshpam_err = pam_get_item(sshpam_handle, PAM_USER, 447 (sshpam_const void **)ptr_pam_user); 448 if (sshpam_err != PAM_SUCCESS) 449 goto auth_fail; 450 451 environ[0] = NULL; 452 if (tz != NULL) 453 if (setenv("TZ", tz, 1) == -1) 454 error("PAM: could not set TZ environment: %s", 455 strerror(errno)); 456 457 if (sshpam_authctxt != NULL) { 458 setproctitle("%s [pam]", 459 sshpam_authctxt->valid ? pam_user : "unknown"); 460 } 461 #endif 462 463 sshpam_conv.conv = sshpam_thread_conv; 464 sshpam_conv.appdata_ptr = ctxt; 465 466 if (sshpam_authctxt == NULL) 467 fatal("%s: PAM authctxt not initialized", __func__); 468 469 buffer_init(&buffer); 470 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 471 (const void *)&sshpam_conv); 472 if (sshpam_err != PAM_SUCCESS) 473 goto auth_fail; 474 sshpam_err = pam_authenticate(sshpam_handle, flags); 475 if (sshpam_err == PAM_MAXTRIES) 476 sshpam_set_maxtries_reached(1); 477 if (sshpam_err != PAM_SUCCESS) 478 goto auth_fail; 479 480 if (!do_pam_account()) { 481 sshpam_err = PAM_ACCT_EXPIRED; 482 goto auth_fail; 483 } 484 if (sshpam_authctxt->force_pwchange) { 485 sshpam_err = pam_chauthtok(sshpam_handle, 486 PAM_CHANGE_EXPIRED_AUTHTOK); 487 if (sshpam_err != PAM_SUCCESS) 488 goto auth_fail; 489 sshpam_password_change_required(0); 490 } 491 492 buffer_put_cstring(&buffer, "OK"); 493 494 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 495 /* Export variables set by do_pam_account */ 496 buffer_put_int(&buffer, sshpam_account_status); 497 buffer_put_int(&buffer, sshpam_authctxt->force_pwchange); 498 499 /* Export any environment strings set in child */ 500 for(i = 0; environ[i] != NULL; i++) 501 ; /* Count */ 502 buffer_put_int(&buffer, i); 503 for(i = 0; environ[i] != NULL; i++) 504 buffer_put_cstring(&buffer, environ[i]); 505 506 /* Export any environment strings set by PAM in child */ 507 env_from_pam = pam_getenvlist(sshpam_handle); 508 for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) 509 ; /* Count */ 510 buffer_put_int(&buffer, i); 511 for(i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) 512 buffer_put_cstring(&buffer, env_from_pam[i]); 513 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */ 514 515 /* XXX - can't do much about an error here */ 516 ssh_msg_send(ctxt->pam_csock, sshpam_err, &buffer); 517 buffer_free(&buffer); 518 pthread_exit(NULL); 519 520 auth_fail: 521 buffer_put_cstring(&buffer, 522 pam_strerror(sshpam_handle, sshpam_err)); 523 /* XXX - can't do much about an error here */ 524 if (sshpam_err == PAM_ACCT_EXPIRED) 525 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, &buffer); 526 else if (sshpam_maxtries_reached) 527 ssh_msg_send(ctxt->pam_csock, PAM_MAXTRIES, &buffer); 528 else 529 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, &buffer); 530 buffer_free(&buffer); 531 pthread_exit(NULL); 532 533 return (NULL); /* Avoid warning for non-pthread case */ 534 } 535 536 void 537 sshpam_thread_cleanup(void) 538 { 539 struct pam_ctxt *ctxt = cleanup_ctxt; 540 541 debug3("PAM: %s entering", __func__); 542 if (ctxt != NULL && ctxt->pam_thread != 0) { 543 pthread_cancel(ctxt->pam_thread); 544 pthread_join(ctxt->pam_thread, NULL); 545 close(ctxt->pam_psock); 546 close(ctxt->pam_csock); 547 memset(ctxt, 0, sizeof(*ctxt)); 548 cleanup_ctxt = NULL; 549 } 550 } 551 552 static int 553 sshpam_null_conv(int n, sshpam_const struct pam_message **msg, 554 struct pam_response **resp, void *data) 555 { 556 debug3("PAM: %s entering, %d messages", __func__, n); 557 return (PAM_CONV_ERR); 558 } 559 560 static struct pam_conv null_conv = { sshpam_null_conv, NULL }; 561 562 static int 563 sshpam_store_conv(int n, sshpam_const struct pam_message **msg, 564 struct pam_response **resp, void *data) 565 { 566 struct pam_response *reply; 567 int i; 568 size_t len; 569 570 debug3("PAM: %s called with %d messages", __func__, n); 571 *resp = NULL; 572 573 if (n <= 0 || n > PAM_MAX_NUM_MSG) 574 return (PAM_CONV_ERR); 575 576 if ((reply = calloc(n, sizeof(*reply))) == NULL) 577 return (PAM_CONV_ERR); 578 579 for (i = 0; i < n; ++i) { 580 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 581 case PAM_ERROR_MSG: 582 case PAM_TEXT_INFO: 583 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 584 buffer_append(&loginmsg, PAM_MSG_MEMBER(msg, i, msg), len); 585 buffer_append(&loginmsg, "\n", 1 ); 586 reply[i].resp_retcode = PAM_SUCCESS; 587 break; 588 default: 589 goto fail; 590 } 591 } 592 *resp = reply; 593 return (PAM_SUCCESS); 594 595 fail: 596 for(i = 0; i < n; i++) { 597 free(reply[i].resp); 598 } 599 free(reply); 600 return (PAM_CONV_ERR); 601 } 602 603 static struct pam_conv store_conv = { sshpam_store_conv, NULL }; 604 605 void 606 sshpam_cleanup(void) 607 { 608 if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor())) 609 return; 610 debug("PAM: cleanup"); 611 pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv); 612 if (sshpam_session_open) { 613 debug("PAM: closing session"); 614 pam_close_session(sshpam_handle, PAM_SILENT); 615 sshpam_session_open = 0; 616 } 617 if (sshpam_cred_established) { 618 debug("PAM: deleting credentials"); 619 pam_setcred(sshpam_handle, PAM_DELETE_CRED); 620 sshpam_cred_established = 0; 621 } 622 sshpam_authenticated = 0; 623 pam_end(sshpam_handle, sshpam_err); 624 sshpam_handle = NULL; 625 } 626 627 static int 628 sshpam_init(Authctxt *authctxt) 629 { 630 const char *pam_rhost, *pam_user, *user = authctxt->user; 631 const char **ptr_pam_user = &pam_user; 632 struct ssh *ssh = active_state; /* XXX */ 633 634 if (sshpam_handle != NULL) { 635 /* We already have a PAM context; check if the user matches */ 636 sshpam_err = pam_get_item(sshpam_handle, 637 PAM_USER, (sshpam_const void **)ptr_pam_user); 638 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0) 639 return (0); 640 pam_end(sshpam_handle, sshpam_err); 641 sshpam_handle = NULL; 642 } 643 debug("PAM: initializing for \"%s\"", user); 644 sshpam_err = 645 pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle); 646 sshpam_authctxt = authctxt; 647 648 if (sshpam_err != PAM_SUCCESS) { 649 pam_end(sshpam_handle, sshpam_err); 650 sshpam_handle = NULL; 651 return (-1); 652 } 653 pam_rhost = auth_get_canonical_hostname(ssh, options.use_dns); 654 debug("PAM: setting PAM_RHOST to \"%s\"", pam_rhost); 655 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, pam_rhost); 656 if (sshpam_err != PAM_SUCCESS) { 657 pam_end(sshpam_handle, sshpam_err); 658 sshpam_handle = NULL; 659 return (-1); 660 } 661 #ifdef PAM_TTY_KLUDGE 662 /* 663 * Some silly PAM modules (e.g. pam_time) require a TTY to operate. 664 * sshd doesn't set the tty until too late in the auth process and 665 * may not even set one (for tty-less connections) 666 */ 667 debug("PAM: setting PAM_TTY to \"ssh\""); 668 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh"); 669 if (sshpam_err != PAM_SUCCESS) { 670 pam_end(sshpam_handle, sshpam_err); 671 sshpam_handle = NULL; 672 return (-1); 673 } 674 #endif 675 return (0); 676 } 677 678 static void * 679 sshpam_init_ctx(Authctxt *authctxt) 680 { 681 struct pam_ctxt *ctxt; 682 int socks[2]; 683 684 debug3("PAM: %s entering", __func__); 685 /* 686 * Refuse to start if we don't have PAM enabled or do_pam_account 687 * has previously failed. 688 */ 689 if (!options.use_pam || sshpam_account_status == 0) 690 return NULL; 691 692 /* Initialize PAM */ 693 if (sshpam_init(authctxt) == -1) { 694 error("PAM: initialization failed"); 695 return (NULL); 696 } 697 698 ctxt = xcalloc(1, sizeof *ctxt); 699 700 /* Start the authentication thread */ 701 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) { 702 error("PAM: failed create sockets: %s", strerror(errno)); 703 free(ctxt); 704 return (NULL); 705 } 706 ctxt->pam_psock = socks[0]; 707 ctxt->pam_csock = socks[1]; 708 if (pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt) == -1) { 709 error("PAM: failed to start authentication thread: %s", 710 strerror(errno)); 711 close(socks[0]); 712 close(socks[1]); 713 free(ctxt); 714 return (NULL); 715 } 716 cleanup_ctxt = ctxt; 717 return (ctxt); 718 } 719 720 static int 721 sshpam_query(void *ctx, char **name, char **info, 722 u_int *num, char ***prompts, u_int **echo_on) 723 { 724 struct ssh *ssh = active_state; /* XXX */ 725 Buffer buffer; 726 struct pam_ctxt *ctxt = ctx; 727 size_t plen; 728 u_char type; 729 char *msg; 730 size_t len, mlen; 731 732 debug3("PAM: %s entering", __func__); 733 buffer_init(&buffer); 734 *name = xstrdup(""); 735 *info = xstrdup(""); 736 *prompts = xmalloc(sizeof(char *)); 737 **prompts = NULL; 738 plen = 0; 739 *echo_on = xmalloc(sizeof(u_int)); 740 while (ssh_msg_recv(ctxt->pam_psock, &buffer) == 0) { 741 type = buffer_get_char(&buffer); 742 msg = buffer_get_string(&buffer, NULL); 743 mlen = strlen(msg); 744 switch (type) { 745 case PAM_PROMPT_ECHO_ON: 746 case PAM_PROMPT_ECHO_OFF: 747 *num = 1; 748 len = plen + mlen + 1; 749 **prompts = xreallocarray(**prompts, 1, len); 750 strlcpy(**prompts + plen, msg, len - plen); 751 plen += mlen; 752 **echo_on = (type == PAM_PROMPT_ECHO_ON); 753 free(msg); 754 return (0); 755 case PAM_ERROR_MSG: 756 case PAM_TEXT_INFO: 757 /* accumulate messages */ 758 len = plen + mlen + 2; 759 **prompts = xreallocarray(**prompts, 1, len); 760 strlcpy(**prompts + plen, msg, len - plen); 761 plen += mlen; 762 strlcat(**prompts + plen, "\n", len - plen); 763 plen++; 764 free(msg); 765 break; 766 case PAM_ACCT_EXPIRED: 767 case PAM_MAXTRIES: 768 if (type == PAM_ACCT_EXPIRED) 769 sshpam_account_status = 0; 770 if (type == PAM_MAXTRIES) 771 sshpam_set_maxtries_reached(1); 772 /* FALLTHROUGH */ 773 case PAM_AUTH_ERR: 774 debug3("PAM: %s", pam_strerror(sshpam_handle, type)); 775 if (**prompts != NULL && strlen(**prompts) != 0) { 776 *info = **prompts; 777 **prompts = NULL; 778 *num = 0; 779 **echo_on = 0; 780 ctxt->pam_done = -1; 781 free(msg); 782 return 0; 783 } 784 /* FALLTHROUGH */ 785 case PAM_SUCCESS: 786 if (**prompts != NULL) { 787 /* drain any accumulated messages */ 788 debug("PAM: %s", **prompts); 789 buffer_append(&loginmsg, **prompts, 790 strlen(**prompts)); 791 free(**prompts); 792 **prompts = NULL; 793 } 794 if (type == PAM_SUCCESS) { 795 if (!sshpam_authctxt->valid || 796 (sshpam_authctxt->pw->pw_uid == 0 && 797 options.permit_root_login != PERMIT_YES)) 798 fatal("Internal error: PAM auth " 799 "succeeded when it should have " 800 "failed"); 801 import_environments(&buffer); 802 *num = 0; 803 **echo_on = 0; 804 ctxt->pam_done = 1; 805 free(msg); 806 return (0); 807 } 808 BLACKLIST_NOTIFY(BLACKLIST_BAD_USER, 809 sshpam_authctxt->user); 810 error("PAM: %s for %s%.100s from %.100s", msg, 811 sshpam_authctxt->valid ? "" : "illegal user ", 812 sshpam_authctxt->user, 813 auth_get_canonical_hostname(ssh, options.use_dns)); 814 /* FALLTHROUGH */ 815 default: 816 *num = 0; 817 **echo_on = 0; 818 free(msg); 819 ctxt->pam_done = -1; 820 return (-1); 821 } 822 } 823 return (-1); 824 } 825 826 /* 827 * Returns a junk password of identical length to that the user supplied. 828 * Used to mitigate timing attacks against crypt(3)/PAM stacks that 829 * vary processing time in proportion to password length. 830 */ 831 static char * 832 fake_password(const char *wire_password) 833 { 834 const char junk[] = "\b\n\r\177INCORRECT"; 835 char *ret = NULL; 836 size_t i, l = wire_password != NULL ? strlen(wire_password) : 0; 837 838 if (l >= INT_MAX) 839 fatal("%s: password length too long: %zu", __func__, l); 840 841 ret = malloc(l + 1); 842 if (ret == NULL) 843 return NULL; 844 for (i = 0; i < l; i++) 845 ret[i] = junk[i % (sizeof(junk) - 1)]; 846 ret[i] = '\0'; 847 return ret; 848 } 849 850 /* XXX - see also comment in auth-chall.c:verify_response */ 851 static int 852 sshpam_respond(void *ctx, u_int num, char **resp) 853 { 854 Buffer buffer; 855 struct pam_ctxt *ctxt = ctx; 856 char *fake; 857 858 debug2("PAM: %s entering, %u responses", __func__, num); 859 switch (ctxt->pam_done) { 860 case 1: 861 sshpam_authenticated = 1; 862 return (0); 863 case 0: 864 break; 865 default: 866 return (-1); 867 } 868 if (num != 1) { 869 error("PAM: expected one response, got %u", num); 870 return (-1); 871 } 872 buffer_init(&buffer); 873 if (sshpam_authctxt->valid && 874 (sshpam_authctxt->pw->pw_uid != 0 || 875 options.permit_root_login == PERMIT_YES)) 876 buffer_put_cstring(&buffer, *resp); 877 else { 878 fake = fake_password(*resp); 879 buffer_put_cstring(&buffer, fake); 880 free(fake); 881 } 882 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, &buffer) == -1) { 883 buffer_free(&buffer); 884 return (-1); 885 } 886 buffer_free(&buffer); 887 return (1); 888 } 889 890 static void 891 sshpam_free_ctx(void *ctxtp) 892 { 893 struct pam_ctxt *ctxt = ctxtp; 894 895 debug3("PAM: %s entering", __func__); 896 sshpam_thread_cleanup(); 897 free(ctxt); 898 /* 899 * We don't call sshpam_cleanup() here because we may need the PAM 900 * handle at a later stage, e.g. when setting up a session. It's 901 * still on the cleanup list, so pam_end() *will* be called before 902 * the server process terminates. 903 */ 904 } 905 906 KbdintDevice sshpam_device = { 907 "pam", 908 sshpam_init_ctx, 909 sshpam_query, 910 sshpam_respond, 911 sshpam_free_ctx 912 }; 913 914 KbdintDevice mm_sshpam_device = { 915 "pam", 916 mm_sshpam_init_ctx, 917 mm_sshpam_query, 918 mm_sshpam_respond, 919 mm_sshpam_free_ctx 920 }; 921 922 /* 923 * This replaces auth-pam.c 924 */ 925 void 926 start_pam(Authctxt *authctxt) 927 { 928 if (!options.use_pam) 929 fatal("PAM: initialisation requested when UsePAM=no"); 930 931 if (sshpam_init(authctxt) == -1) 932 fatal("PAM: initialisation failed"); 933 } 934 935 void 936 finish_pam(void) 937 { 938 sshpam_cleanup(); 939 } 940 941 static void 942 expose_authinfo(const char *caller) 943 { 944 char *auth_info; 945 946 /* 947 * Expose authentication information to PAM. 948 * The enviornment variable is versioned. Please increment the 949 * version suffix if the format of session_info changes. 950 */ 951 if (sshpam_authctxt->session_info == NULL) 952 auth_info = xstrdup(""); 953 else if ((auth_info = sshbuf_dup_string( 954 sshpam_authctxt->session_info)) == NULL) 955 fatal("%s: sshbuf_dup_string failed", __func__); 956 957 debug2("%s: auth information in SSH_AUTH_INFO_0", caller); 958 do_pam_putenv("SSH_AUTH_INFO_0", auth_info); 959 free(auth_info); 960 } 961 962 u_int 963 do_pam_account(void) 964 { 965 debug("%s: called", __func__); 966 if (sshpam_account_status != -1) 967 return (sshpam_account_status); 968 969 expose_authinfo(__func__); 970 971 sshpam_err = pam_acct_mgmt(sshpam_handle, 0); 972 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err, 973 pam_strerror(sshpam_handle, sshpam_err)); 974 975 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) { 976 sshpam_account_status = 0; 977 return (sshpam_account_status); 978 } 979 980 if (sshpam_err == PAM_NEW_AUTHTOK_REQD) 981 sshpam_password_change_required(1); 982 983 sshpam_account_status = 1; 984 return (sshpam_account_status); 985 } 986 987 void 988 do_pam_setcred(int init) 989 { 990 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 991 (const void *)&store_conv); 992 if (sshpam_err != PAM_SUCCESS) 993 fatal("PAM: failed to set PAM_CONV: %s", 994 pam_strerror(sshpam_handle, sshpam_err)); 995 if (init) { 996 debug("PAM: establishing credentials"); 997 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED); 998 } else { 999 debug("PAM: reinitializing credentials"); 1000 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED); 1001 } 1002 if (sshpam_err == PAM_SUCCESS) { 1003 sshpam_cred_established = 1; 1004 return; 1005 } 1006 if (sshpam_authenticated) 1007 fatal("PAM: pam_setcred(): %s", 1008 pam_strerror(sshpam_handle, sshpam_err)); 1009 else 1010 debug("PAM: pam_setcred(): %s", 1011 pam_strerror(sshpam_handle, sshpam_err)); 1012 } 1013 1014 static int 1015 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg, 1016 struct pam_response **resp, void *data) 1017 { 1018 char input[PAM_MAX_MSG_SIZE]; 1019 struct pam_response *reply; 1020 int i; 1021 1022 debug3("PAM: %s called with %d messages", __func__, n); 1023 1024 *resp = NULL; 1025 1026 if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO)) 1027 return (PAM_CONV_ERR); 1028 1029 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1030 return (PAM_CONV_ERR); 1031 1032 for (i = 0; i < n; ++i) { 1033 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1034 case PAM_PROMPT_ECHO_OFF: 1035 reply[i].resp = 1036 read_passphrase(PAM_MSG_MEMBER(msg, i, msg), 1037 RP_ALLOW_STDIN); 1038 reply[i].resp_retcode = PAM_SUCCESS; 1039 break; 1040 case PAM_PROMPT_ECHO_ON: 1041 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1042 if (fgets(input, sizeof input, stdin) == NULL) 1043 input[0] = '\0'; 1044 if ((reply[i].resp = strdup(input)) == NULL) 1045 goto fail; 1046 reply[i].resp_retcode = PAM_SUCCESS; 1047 break; 1048 case PAM_ERROR_MSG: 1049 case PAM_TEXT_INFO: 1050 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1051 reply[i].resp_retcode = PAM_SUCCESS; 1052 break; 1053 default: 1054 goto fail; 1055 } 1056 } 1057 *resp = reply; 1058 return (PAM_SUCCESS); 1059 1060 fail: 1061 for(i = 0; i < n; i++) { 1062 free(reply[i].resp); 1063 } 1064 free(reply); 1065 return (PAM_CONV_ERR); 1066 } 1067 1068 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL }; 1069 1070 /* 1071 * XXX this should be done in the authentication phase, but ssh1 doesn't 1072 * support that 1073 */ 1074 void 1075 do_pam_chauthtok(void) 1076 { 1077 if (use_privsep) 1078 fatal("Password expired (unable to change with privsep)"); 1079 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1080 (const void *)&tty_conv); 1081 if (sshpam_err != PAM_SUCCESS) 1082 fatal("PAM: failed to set PAM_CONV: %s", 1083 pam_strerror(sshpam_handle, sshpam_err)); 1084 debug("PAM: changing password"); 1085 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK); 1086 if (sshpam_err != PAM_SUCCESS) 1087 fatal("PAM: pam_chauthtok(): %s", 1088 pam_strerror(sshpam_handle, sshpam_err)); 1089 } 1090 1091 void 1092 do_pam_session(struct ssh *ssh) 1093 { 1094 debug3("PAM: opening session"); 1095 1096 expose_authinfo(__func__); 1097 1098 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1099 (const void *)&store_conv); 1100 if (sshpam_err != PAM_SUCCESS) 1101 fatal("PAM: failed to set PAM_CONV: %s", 1102 pam_strerror(sshpam_handle, sshpam_err)); 1103 sshpam_err = pam_open_session(sshpam_handle, 0); 1104 if (sshpam_err == PAM_SUCCESS) 1105 sshpam_session_open = 1; 1106 else { 1107 sshpam_session_open = 0; 1108 auth_restrict_session(ssh); 1109 error("PAM: pam_open_session(): %s", 1110 pam_strerror(sshpam_handle, sshpam_err)); 1111 } 1112 1113 } 1114 1115 int 1116 is_pam_session_open(void) 1117 { 1118 return sshpam_session_open; 1119 } 1120 1121 /* 1122 * Set a PAM environment string. We need to do this so that the session 1123 * modules can handle things like Kerberos/GSI credentials that appear 1124 * during the ssh authentication process. 1125 */ 1126 int 1127 do_pam_putenv(char *name, char *value) 1128 { 1129 int ret = 1; 1130 #ifdef HAVE_PAM_PUTENV 1131 char *compound; 1132 size_t len; 1133 1134 len = strlen(name) + strlen(value) + 2; 1135 compound = xmalloc(len); 1136 1137 snprintf(compound, len, "%s=%s", name, value); 1138 ret = pam_putenv(sshpam_handle, compound); 1139 free(compound); 1140 #endif 1141 1142 return (ret); 1143 } 1144 1145 char ** 1146 fetch_pam_child_environment(void) 1147 { 1148 return sshpam_env; 1149 } 1150 1151 char ** 1152 fetch_pam_environment(void) 1153 { 1154 return (pam_getenvlist(sshpam_handle)); 1155 } 1156 1157 void 1158 free_pam_environment(char **env) 1159 { 1160 char **envp; 1161 1162 if (env == NULL) 1163 return; 1164 1165 for (envp = env; *envp; envp++) 1166 free(*envp); 1167 free(env); 1168 } 1169 1170 /* 1171 * "Blind" conversation function for password authentication. Assumes that 1172 * echo-off prompts are for the password and stores messages for later 1173 * display. 1174 */ 1175 static int 1176 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg, 1177 struct pam_response **resp, void *data) 1178 { 1179 struct pam_response *reply; 1180 int i; 1181 size_t len; 1182 1183 debug3("PAM: %s called with %d messages", __func__, n); 1184 1185 *resp = NULL; 1186 1187 if (n <= 0 || n > PAM_MAX_NUM_MSG) 1188 return (PAM_CONV_ERR); 1189 1190 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1191 return (PAM_CONV_ERR); 1192 1193 for (i = 0; i < n; ++i) { 1194 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1195 case PAM_PROMPT_ECHO_OFF: 1196 if (sshpam_password == NULL) 1197 goto fail; 1198 if ((reply[i].resp = strdup(sshpam_password)) == NULL) 1199 goto fail; 1200 reply[i].resp_retcode = PAM_SUCCESS; 1201 break; 1202 case PAM_ERROR_MSG: 1203 case PAM_TEXT_INFO: 1204 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 1205 if (len > 0) { 1206 buffer_append(&loginmsg, 1207 PAM_MSG_MEMBER(msg, i, msg), len); 1208 buffer_append(&loginmsg, "\n", 1); 1209 } 1210 if ((reply[i].resp = strdup("")) == NULL) 1211 goto fail; 1212 reply[i].resp_retcode = PAM_SUCCESS; 1213 break; 1214 default: 1215 goto fail; 1216 } 1217 } 1218 *resp = reply; 1219 return (PAM_SUCCESS); 1220 1221 fail: 1222 for(i = 0; i < n; i++) { 1223 free(reply[i].resp); 1224 } 1225 free(reply); 1226 return (PAM_CONV_ERR); 1227 } 1228 1229 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL }; 1230 1231 /* 1232 * Attempt password authentication via PAM 1233 */ 1234 int 1235 sshpam_auth_passwd(Authctxt *authctxt, const char *password) 1236 { 1237 int flags = (options.permit_empty_passwd == 0 ? 1238 PAM_DISALLOW_NULL_AUTHTOK : 0); 1239 char *fake = NULL; 1240 1241 if (!options.use_pam || sshpam_handle == NULL) 1242 fatal("PAM: %s called when PAM disabled or failed to " 1243 "initialise.", __func__); 1244 1245 sshpam_password = password; 1246 sshpam_authctxt = authctxt; 1247 1248 /* 1249 * If the user logging in is invalid, or is root but is not permitted 1250 * by PermitRootLogin, use an invalid password to prevent leaking 1251 * information via timing (eg if the PAM config has a delay on fail). 1252 */ 1253 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 && 1254 options.permit_root_login != PERMIT_YES)) 1255 sshpam_password = fake = fake_password(password); 1256 1257 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1258 (const void *)&passwd_conv); 1259 if (sshpam_err != PAM_SUCCESS) 1260 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__, 1261 pam_strerror(sshpam_handle, sshpam_err)); 1262 1263 sshpam_err = pam_authenticate(sshpam_handle, flags); 1264 sshpam_password = NULL; 1265 free(fake); 1266 if (sshpam_err == PAM_MAXTRIES) 1267 sshpam_set_maxtries_reached(1); 1268 if (sshpam_err == PAM_SUCCESS && authctxt->valid) { 1269 debug("PAM: password authentication accepted for %.100s", 1270 authctxt->user); 1271 return 1; 1272 } else { 1273 debug("PAM: password authentication failed for %.100s: %s", 1274 authctxt->valid ? authctxt->user : "an illegal user", 1275 pam_strerror(sshpam_handle, sshpam_err)); 1276 return 0; 1277 } 1278 } 1279 1280 int 1281 sshpam_get_maxtries_reached(void) 1282 { 1283 return sshpam_maxtries_reached; 1284 } 1285 1286 void 1287 sshpam_set_maxtries_reached(int reached) 1288 { 1289 if (reached == 0 || sshpam_maxtries_reached) 1290 return; 1291 sshpam_maxtries_reached = 1; 1292 options.password_authentication = 0; 1293 options.kbd_interactive_authentication = 0; 1294 options.challenge_response_authentication = 0; 1295 } 1296 #endif /* USE_PAM */ 1297