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 <stdlib.h> 60 #include <string.h> 61 #include <unistd.h> 62 63 #ifdef USE_PAM 64 #if defined(HAVE_SECURITY_PAM_APPL_H) 65 #include <security/pam_appl.h> 66 #elif defined (HAVE_PAM_PAM_APPL_H) 67 #include <pam/pam_appl.h> 68 #endif 69 70 #if !defined(SSHD_PAM_SERVICE) 71 extern char *__progname; 72 # define SSHD_PAM_SERVICE __progname 73 #endif 74 75 /* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */ 76 #ifdef PAM_SUN_CODEBASE 77 # define sshpam_const /* Solaris, HP-UX, SunOS */ 78 #else 79 # define sshpam_const const /* LinuxPAM, OpenPAM, AIX */ 80 #endif 81 82 /* Ambiguity in spec: is it an array of pointers or a pointer to an array? */ 83 #ifdef PAM_SUN_CODEBASE 84 # define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member) 85 #else 86 # define PAM_MSG_MEMBER(msg, n, member) ((msg)[(n)]->member) 87 #endif 88 89 #include "xmalloc.h" 90 #include "sshbuf.h" 91 #include "ssherr.h" 92 #include "hostfile.h" 93 #include "auth.h" 94 #include "auth-pam.h" 95 #include "canohost.h" 96 #include "log.h" 97 #include "msg.h" 98 #include "packet.h" 99 #include "misc.h" 100 #include "servconf.h" 101 #include "ssh2.h" 102 #include "auth-options.h" 103 #include "misc.h" 104 #ifdef GSSAPI 105 #include "ssh-gss.h" 106 #endif 107 #include "monitor_wrap.h" 108 109 extern ServerOptions options; 110 extern struct sshbuf *loginmsg; 111 extern u_int utmp_len; 112 113 /* so we don't silently change behaviour */ 114 #ifdef USE_POSIX_THREADS 115 # error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK" 116 #endif 117 118 /* 119 * Formerly known as USE_POSIX_THREADS, using this is completely unsupported 120 * and generally a bad idea. Use at own risk and do not expect support if 121 * this breaks. 122 */ 123 #ifdef UNSUPPORTED_POSIX_THREADS_HACK 124 #include <pthread.h> 125 /* 126 * Avoid namespace clash when *not* using pthreads for systems *with* 127 * pthreads, which unconditionally define pthread_t via sys/types.h 128 * (e.g. Linux) 129 */ 130 typedef pthread_t sp_pthread_t; 131 #else 132 typedef pid_t sp_pthread_t; 133 #define pthread_exit fake_pthread_exit 134 #define pthread_create fake_pthread_create 135 #define pthread_cancel fake_pthread_cancel 136 #define pthread_join fake_pthread_join 137 #endif 138 139 struct pam_ctxt { 140 sp_pthread_t pam_thread; 141 int pam_psock; 142 int pam_csock; 143 int pam_done; 144 }; 145 146 static void sshpam_free_ctx(void *); 147 static struct pam_ctxt *cleanup_ctxt; 148 149 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 150 /* 151 * Simulate threads with processes. 152 */ 153 154 static int sshpam_thread_status = -1; 155 static sshsig_t sshpam_oldsig; 156 157 static void 158 sshpam_sigchld_handler(int sig) 159 { 160 ssh_signal(SIGCHLD, SIG_DFL); 161 if (cleanup_ctxt == NULL) 162 return; /* handler called after PAM cleanup, shouldn't happen */ 163 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG) 164 <= 0) { 165 /* PAM thread has not exitted, privsep slave must have */ 166 kill(cleanup_ctxt->pam_thread, SIGTERM); 167 while (waitpid(cleanup_ctxt->pam_thread, 168 &sshpam_thread_status, 0) == -1) { 169 if (errno == EINTR) 170 continue; 171 return; 172 } 173 } 174 if (WIFSIGNALED(sshpam_thread_status) && 175 WTERMSIG(sshpam_thread_status) == SIGTERM) 176 return; /* terminated by pthread_cancel */ 177 if (!WIFEXITED(sshpam_thread_status)) 178 sigdie("PAM: authentication thread exited unexpectedly"); 179 if (WEXITSTATUS(sshpam_thread_status) != 0) 180 sigdie("PAM: authentication thread exited uncleanly"); 181 } 182 183 /* ARGSUSED */ 184 static void 185 pthread_exit(void *value) 186 { 187 _exit(0); 188 } 189 190 /* ARGSUSED */ 191 static int 192 pthread_create(sp_pthread_t *thread, const void *attr, 193 void *(*thread_start)(void *), void *arg) 194 { 195 pid_t pid; 196 struct pam_ctxt *ctx = arg; 197 198 sshpam_thread_status = -1; 199 switch ((pid = fork())) { 200 case -1: 201 error("fork(): %s", strerror(errno)); 202 return errno; 203 case 0: 204 close(ctx->pam_psock); 205 ctx->pam_psock = -1; 206 thread_start(arg); 207 _exit(1); 208 default: 209 *thread = pid; 210 close(ctx->pam_csock); 211 ctx->pam_csock = -1; 212 sshpam_oldsig = ssh_signal(SIGCHLD, sshpam_sigchld_handler); 213 return (0); 214 } 215 } 216 217 static int 218 pthread_cancel(sp_pthread_t thread) 219 { 220 ssh_signal(SIGCHLD, sshpam_oldsig); 221 return (kill(thread, SIGTERM)); 222 } 223 224 /* ARGSUSED */ 225 static int 226 pthread_join(sp_pthread_t thread, void **value) 227 { 228 int status; 229 230 if (sshpam_thread_status != -1) 231 return (sshpam_thread_status); 232 ssh_signal(SIGCHLD, sshpam_oldsig); 233 while (waitpid(thread, &status, 0) == -1) { 234 if (errno == EINTR) 235 continue; 236 fatal("%s: waitpid: %s", __func__, strerror(errno)); 237 } 238 return (status); 239 } 240 #endif 241 242 243 static pam_handle_t *sshpam_handle = NULL; 244 static int sshpam_err = 0; 245 static int sshpam_authenticated = 0; 246 static int sshpam_session_open = 0; 247 static int sshpam_cred_established = 0; 248 static int sshpam_account_status = -1; 249 static int sshpam_maxtries_reached = 0; 250 static char **sshpam_env = NULL; 251 static Authctxt *sshpam_authctxt = NULL; 252 static const char *sshpam_password = NULL; 253 static char *sshpam_rhost = NULL; 254 static char *sshpam_laddr = NULL; 255 static char *sshpam_conninfo = NULL; 256 257 /* Some PAM implementations don't implement this */ 258 #ifndef HAVE_PAM_GETENVLIST 259 static char ** 260 pam_getenvlist(pam_handle_t *pamh) 261 { 262 /* 263 * XXX - If necessary, we can still support environment passing 264 * for platforms without pam_getenvlist by searching for known 265 * env vars (e.g. KRB5CCNAME) from the PAM environment. 266 */ 267 return NULL; 268 } 269 #endif 270 271 #ifndef HAVE_PAM_PUTENV 272 static int 273 pam_putenv(pam_handle_t *pamh, const char *name_value) 274 { 275 return PAM_SUCCESS; 276 } 277 #endif /* HAVE_PAM_PUTENV */ 278 279 /* 280 * Some platforms, notably Solaris, do not enforce password complexity 281 * rules during pam_chauthtok() if the real uid of the calling process 282 * is 0, on the assumption that it's being called by "passwd" run by root. 283 * This wraps pam_chauthtok and sets/restore the real uid so PAM will do 284 * the right thing. 285 */ 286 #ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID 287 static int 288 sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags) 289 { 290 int result; 291 292 if (sshpam_authctxt == NULL) 293 fatal("PAM: sshpam_authctxt not initialized"); 294 if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1) 295 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 296 result = pam_chauthtok(pamh, flags); 297 if (setreuid(0, -1) == -1) 298 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 299 return result; 300 } 301 # define pam_chauthtok(a,b) (sshpam_chauthtok_ruid((a), (b))) 302 #endif 303 304 static void 305 sshpam_password_change_required(int reqd) 306 { 307 extern struct sshauthopt *auth_opts; 308 static int saved_port, saved_agent, saved_x11; 309 310 debug3("%s %d", __func__, reqd); 311 if (sshpam_authctxt == NULL) 312 fatal("%s: PAM authctxt not initialized", __func__); 313 sshpam_authctxt->force_pwchange = reqd; 314 if (reqd) { 315 saved_port = auth_opts->permit_port_forwarding_flag; 316 saved_agent = auth_opts->permit_agent_forwarding_flag; 317 saved_x11 = auth_opts->permit_x11_forwarding_flag; 318 auth_opts->permit_port_forwarding_flag = 0; 319 auth_opts->permit_agent_forwarding_flag = 0; 320 auth_opts->permit_x11_forwarding_flag = 0; 321 } else { 322 if (saved_port) 323 auth_opts->permit_port_forwarding_flag = saved_port; 324 if (saved_agent) 325 auth_opts->permit_agent_forwarding_flag = saved_agent; 326 if (saved_x11) 327 auth_opts->permit_x11_forwarding_flag = saved_x11; 328 } 329 } 330 331 /* Import regular and PAM environment from subprocess */ 332 static void 333 import_environments(struct sshbuf *b) 334 { 335 char *env; 336 u_int n, i, num_env; 337 int r; 338 339 debug3("PAM: %s entering", __func__); 340 341 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 342 /* Import variables set by do_pam_account */ 343 if ((r = sshbuf_get_u32(b, &n)) != 0) 344 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 345 if (n > INT_MAX) 346 fatal("%s: invalid PAM account status %u", __func__, n); 347 sshpam_account_status = (int)n; 348 if ((r = sshbuf_get_u32(b, &n)) != 0) 349 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 350 sshpam_password_change_required(n != 0); 351 352 /* Import environment from subprocess */ 353 if ((r = sshbuf_get_u32(b, &num_env)) != 0) 354 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 355 if (num_env > 1024) 356 fatal("%s: received %u environment variables, expected <= 1024", 357 __func__, num_env); 358 sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env)); 359 debug3("PAM: num env strings %d", num_env); 360 for(i = 0; i < num_env; i++) { 361 if ((r = sshbuf_get_cstring(b, &(sshpam_env[i]), NULL)) != 0) 362 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 363 } 364 sshpam_env[num_env] = NULL; 365 366 /* Import PAM environment from subprocess */ 367 if ((r = sshbuf_get_u32(b, &num_env)) != 0) 368 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 369 debug("PAM: num PAM env strings %d", num_env); 370 for (i = 0; i < num_env; i++) { 371 if ((r = sshbuf_get_cstring(b, &env, NULL)) != 0) 372 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 373 /* Errors are not fatal here */ 374 if ((r = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) { 375 error("PAM: pam_putenv: %s", 376 pam_strerror(sshpam_handle, r)); 377 } 378 /* 379 * XXX this possibly leaks env because it is not documented 380 * what pam_putenv() does with it. Does it copy it? Does it 381 * take ownweship? We don't know, so it's safest just to leak. 382 */ 383 } 384 #endif 385 } 386 387 /* 388 * Conversation function for authentication thread. 389 */ 390 static int 391 sshpam_thread_conv(int n, sshpam_const struct pam_message **msg, 392 struct pam_response **resp, void *data) 393 { 394 struct sshbuf *buffer; 395 struct pam_ctxt *ctxt; 396 struct pam_response *reply; 397 int r, i; 398 u_char status; 399 400 debug3("PAM: %s entering, %d messages", __func__, n); 401 *resp = NULL; 402 403 if (data == NULL) { 404 error("PAM: conversation function passed a null context"); 405 return (PAM_CONV_ERR); 406 } 407 ctxt = data; 408 if (n <= 0 || n > PAM_MAX_NUM_MSG) 409 return (PAM_CONV_ERR); 410 411 if ((reply = calloc(n, sizeof(*reply))) == NULL) 412 return PAM_CONV_ERR; 413 if ((buffer = sshbuf_new()) == NULL) { 414 free(reply); 415 return PAM_CONV_ERR; 416 } 417 418 for (i = 0; i < n; ++i) { 419 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 420 case PAM_PROMPT_ECHO_OFF: 421 case PAM_PROMPT_ECHO_ON: 422 if ((r = sshbuf_put_cstring(buffer, 423 PAM_MSG_MEMBER(msg, i, msg))) != 0) 424 fatal("%s: buffer error: %s", 425 __func__, ssh_err(r)); 426 if (ssh_msg_send(ctxt->pam_csock, 427 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1) 428 goto fail; 429 430 if (ssh_msg_recv(ctxt->pam_csock, buffer) == -1) 431 goto fail; 432 if ((r = sshbuf_get_u8(buffer, &status)) != 0) 433 fatal("%s: buffer error: %s", 434 __func__, ssh_err(r)); 435 if (status != PAM_AUTHTOK) 436 goto fail; 437 if ((r = sshbuf_get_cstring(buffer, 438 &reply[i].resp, NULL)) != 0) 439 fatal("%s: buffer error: %s", 440 __func__, ssh_err(r)); 441 break; 442 case PAM_ERROR_MSG: 443 case PAM_TEXT_INFO: 444 if ((r = sshbuf_put_cstring(buffer, 445 PAM_MSG_MEMBER(msg, i, msg))) != 0) 446 fatal("%s: buffer error: %s", 447 __func__, ssh_err(r)); 448 if (ssh_msg_send(ctxt->pam_csock, 449 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1) 450 goto fail; 451 break; 452 default: 453 goto fail; 454 } 455 sshbuf_reset(buffer); 456 } 457 sshbuf_free(buffer); 458 *resp = reply; 459 return (PAM_SUCCESS); 460 461 fail: 462 for(i = 0; i < n; i++) { 463 free(reply[i].resp); 464 } 465 free(reply); 466 sshbuf_free(buffer); 467 return (PAM_CONV_ERR); 468 } 469 470 /* 471 * Authentication thread. 472 */ 473 static void * 474 sshpam_thread(void *ctxtp) 475 { 476 struct pam_ctxt *ctxt = ctxtp; 477 struct sshbuf *buffer = NULL; 478 struct pam_conv sshpam_conv; 479 int r, flags = (options.permit_empty_passwd == 0 ? 480 PAM_DISALLOW_NULL_AUTHTOK : 0); 481 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 482 extern char **environ; 483 char **env_from_pam; 484 u_int i; 485 const char *pam_user; 486 const char **ptr_pam_user = &pam_user; 487 char *tz = getenv("TZ"); 488 489 sshpam_err = pam_get_item(sshpam_handle, PAM_USER, 490 (sshpam_const void **)ptr_pam_user); 491 if (sshpam_err != PAM_SUCCESS) 492 goto auth_fail; 493 494 environ[0] = NULL; 495 if (tz != NULL) 496 if (setenv("TZ", tz, 1) == -1) 497 error("PAM: could not set TZ environment: %s", 498 strerror(errno)); 499 500 if (sshpam_authctxt != NULL) { 501 setproctitle("%s [pam]", 502 sshpam_authctxt->valid ? pam_user : "unknown"); 503 } 504 #endif 505 506 sshpam_conv.conv = sshpam_thread_conv; 507 sshpam_conv.appdata_ptr = ctxt; 508 509 if (sshpam_authctxt == NULL) 510 fatal("%s: PAM authctxt not initialized", __func__); 511 512 if ((buffer = sshbuf_new()) == NULL) 513 fatal("%s: sshbuf_new failed", __func__); 514 515 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 516 (const void *)&sshpam_conv); 517 if (sshpam_err != PAM_SUCCESS) 518 goto auth_fail; 519 sshpam_err = pam_authenticate(sshpam_handle, flags); 520 if (sshpam_err == PAM_MAXTRIES) 521 sshpam_set_maxtries_reached(1); 522 if (sshpam_err != PAM_SUCCESS) 523 goto auth_fail; 524 525 if (!do_pam_account()) { 526 sshpam_err = PAM_ACCT_EXPIRED; 527 goto auth_fail; 528 } 529 if (sshpam_authctxt->force_pwchange) { 530 sshpam_err = pam_chauthtok(sshpam_handle, 531 PAM_CHANGE_EXPIRED_AUTHTOK); 532 if (sshpam_err != PAM_SUCCESS) 533 goto auth_fail; 534 sshpam_password_change_required(0); 535 } 536 537 if ((r = sshbuf_put_cstring(buffer, "OK")) != 0) 538 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 539 540 #ifndef UNSUPPORTED_POSIX_THREADS_HACK 541 /* Export variables set by do_pam_account */ 542 if ((r = sshbuf_put_u32(buffer, sshpam_account_status)) != 0 || 543 (r = sshbuf_put_u32(buffer, sshpam_authctxt->force_pwchange)) != 0) 544 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 545 546 /* Export any environment strings set in child */ 547 for (i = 0; environ[i] != NULL; i++) { 548 /* Count */ 549 if (i > INT_MAX) 550 fatal("%s: too many environment strings", __func__); 551 } 552 if ((r = sshbuf_put_u32(buffer, i)) != 0) 553 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 554 for (i = 0; environ[i] != NULL; i++) { 555 if ((r = sshbuf_put_cstring(buffer, environ[i])) != 0) 556 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 557 } 558 /* Export any environment strings set by PAM in child */ 559 env_from_pam = pam_getenvlist(sshpam_handle); 560 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) { 561 /* Count */ 562 if (i > INT_MAX) 563 fatal("%s: too many PAM environment strings", __func__); 564 } 565 if ((r = sshbuf_put_u32(buffer, i)) != 0) 566 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 567 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) { 568 if ((r = sshbuf_put_cstring(buffer, env_from_pam[i])) != 0) 569 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 570 } 571 #endif /* UNSUPPORTED_POSIX_THREADS_HACK */ 572 573 /* XXX - can't do much about an error here */ 574 ssh_msg_send(ctxt->pam_csock, sshpam_err, buffer); 575 sshbuf_free(buffer); 576 pthread_exit(NULL); 577 578 auth_fail: 579 if ((r = sshbuf_put_cstring(buffer, 580 pam_strerror(sshpam_handle, sshpam_err))) != 0) 581 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 582 /* XXX - can't do much about an error here */ 583 if (sshpam_err == PAM_ACCT_EXPIRED) 584 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, buffer); 585 else if (sshpam_maxtries_reached) 586 ssh_msg_send(ctxt->pam_csock, PAM_MAXTRIES, buffer); 587 else 588 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, buffer); 589 sshbuf_free(buffer); 590 pthread_exit(NULL); 591 592 return (NULL); /* Avoid warning for non-pthread case */ 593 } 594 595 void 596 sshpam_thread_cleanup(void) 597 { 598 struct pam_ctxt *ctxt = cleanup_ctxt; 599 600 debug3("PAM: %s entering", __func__); 601 if (ctxt != NULL && ctxt->pam_thread != 0) { 602 pthread_cancel(ctxt->pam_thread); 603 pthread_join(ctxt->pam_thread, NULL); 604 close(ctxt->pam_psock); 605 close(ctxt->pam_csock); 606 memset(ctxt, 0, sizeof(*ctxt)); 607 cleanup_ctxt = NULL; 608 } 609 } 610 611 static int 612 sshpam_null_conv(int n, sshpam_const struct pam_message **msg, 613 struct pam_response **resp, void *data) 614 { 615 debug3("PAM: %s entering, %d messages", __func__, n); 616 return (PAM_CONV_ERR); 617 } 618 619 static struct pam_conv null_conv = { sshpam_null_conv, NULL }; 620 621 static int 622 sshpam_store_conv(int n, sshpam_const struct pam_message **msg, 623 struct pam_response **resp, void *data) 624 { 625 struct pam_response *reply; 626 int r, i; 627 628 debug3("PAM: %s called with %d messages", __func__, n); 629 *resp = NULL; 630 631 if (n <= 0 || n > PAM_MAX_NUM_MSG) 632 return (PAM_CONV_ERR); 633 634 if ((reply = calloc(n, sizeof(*reply))) == NULL) 635 return (PAM_CONV_ERR); 636 637 for (i = 0; i < n; ++i) { 638 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 639 case PAM_ERROR_MSG: 640 case PAM_TEXT_INFO: 641 if ((r = sshbuf_putf(loginmsg, "%s\n", 642 PAM_MSG_MEMBER(msg, i, msg))) != 0) 643 fatal("%s: buffer error: %s", 644 __func__, ssh_err(r)); 645 reply[i].resp_retcode = PAM_SUCCESS; 646 break; 647 default: 648 goto fail; 649 } 650 } 651 *resp = reply; 652 return (PAM_SUCCESS); 653 654 fail: 655 for(i = 0; i < n; i++) { 656 free(reply[i].resp); 657 } 658 free(reply); 659 return (PAM_CONV_ERR); 660 } 661 662 static struct pam_conv store_conv = { sshpam_store_conv, NULL }; 663 664 void 665 sshpam_cleanup(void) 666 { 667 if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor())) 668 return; 669 debug("PAM: cleanup"); 670 pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv); 671 if (sshpam_session_open) { 672 debug("PAM: closing session"); 673 pam_close_session(sshpam_handle, PAM_SILENT); 674 sshpam_session_open = 0; 675 } 676 if (sshpam_cred_established) { 677 debug("PAM: deleting credentials"); 678 pam_setcred(sshpam_handle, PAM_DELETE_CRED); 679 sshpam_cred_established = 0; 680 } 681 sshpam_authenticated = 0; 682 pam_end(sshpam_handle, sshpam_err); 683 sshpam_handle = NULL; 684 } 685 686 static int 687 sshpam_init(struct ssh *ssh, Authctxt *authctxt) 688 { 689 const char *pam_user, *user = authctxt->user; 690 const char **ptr_pam_user = &pam_user; 691 692 #if defined(PAM_SUN_CODEBASE) && defined(PAM_MAX_RESP_SIZE) 693 /* Protect buggy PAM implementations from excessively long usernames */ 694 if (strlen(user) >= PAM_MAX_RESP_SIZE) 695 fatal("Username too long from %s port %d", 696 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 697 #endif 698 if (sshpam_handle == NULL) { 699 if (ssh == NULL) { 700 fatal("%s: called initially with no " 701 "packet context", __func__); 702 } 703 } if (sshpam_handle != NULL) { 704 /* We already have a PAM context; check if the user matches */ 705 sshpam_err = pam_get_item(sshpam_handle, 706 PAM_USER, (sshpam_const void **)ptr_pam_user); 707 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0) 708 return (0); 709 pam_end(sshpam_handle, sshpam_err); 710 sshpam_handle = NULL; 711 } 712 debug("PAM: initializing for \"%s\"", user); 713 sshpam_err = 714 pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle); 715 sshpam_authctxt = authctxt; 716 717 if (sshpam_err != PAM_SUCCESS) { 718 pam_end(sshpam_handle, sshpam_err); 719 sshpam_handle = NULL; 720 return (-1); 721 } 722 723 if (ssh != NULL && sshpam_rhost == NULL) { 724 /* 725 * We need to cache these as we don't have packet context 726 * during the kbdint flow. 727 */ 728 sshpam_rhost = xstrdup(auth_get_canonical_hostname(ssh, 729 options.use_dns)); 730 sshpam_laddr = get_local_ipaddr( 731 ssh_packet_get_connection_in(ssh)); 732 xasprintf(&sshpam_conninfo, "SSH_CONNECTION=%.50s %d %.50s %d", 733 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 734 sshpam_laddr, ssh_local_port(ssh)); 735 } 736 if (sshpam_rhost != NULL) { 737 debug("PAM: setting PAM_RHOST to \"%s\"", sshpam_rhost); 738 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, 739 sshpam_rhost); 740 if (sshpam_err != PAM_SUCCESS) { 741 pam_end(sshpam_handle, sshpam_err); 742 sshpam_handle = NULL; 743 return (-1); 744 } 745 /* Put SSH_CONNECTION in the PAM environment too */ 746 pam_putenv(sshpam_handle, sshpam_conninfo); 747 } 748 749 #ifdef PAM_TTY_KLUDGE 750 /* 751 * Some silly PAM modules (e.g. pam_time) require a TTY to operate. 752 * sshd doesn't set the tty until too late in the auth process and 753 * may not even set one (for tty-less connections) 754 */ 755 debug("PAM: setting PAM_TTY to \"ssh\""); 756 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh"); 757 if (sshpam_err != PAM_SUCCESS) { 758 pam_end(sshpam_handle, sshpam_err); 759 sshpam_handle = NULL; 760 return (-1); 761 } 762 #endif 763 return (0); 764 } 765 766 static void 767 expose_authinfo(const char *caller) 768 { 769 char *auth_info; 770 771 /* 772 * Expose authentication information to PAM. 773 * The environment variable is versioned. Please increment the 774 * version suffix if the format of session_info changes. 775 */ 776 if (sshpam_authctxt->session_info == NULL) 777 auth_info = xstrdup(""); 778 else if ((auth_info = sshbuf_dup_string( 779 sshpam_authctxt->session_info)) == NULL) 780 fatal("%s: sshbuf_dup_string failed", __func__); 781 782 debug2("%s: auth information in SSH_AUTH_INFO_0", caller); 783 do_pam_putenv("SSH_AUTH_INFO_0", auth_info); 784 free(auth_info); 785 } 786 787 static void * 788 sshpam_init_ctx(Authctxt *authctxt) 789 { 790 struct pam_ctxt *ctxt; 791 int result, socks[2]; 792 793 debug3("PAM: %s entering", __func__); 794 /* 795 * Refuse to start if we don't have PAM enabled or do_pam_account 796 * has previously failed. 797 */ 798 if (!options.use_pam || sshpam_account_status == 0) 799 return NULL; 800 801 /* Initialize PAM */ 802 if (sshpam_init(NULL, authctxt) == -1) { 803 error("PAM: initialization failed"); 804 return (NULL); 805 } 806 807 expose_authinfo(__func__); 808 ctxt = xcalloc(1, sizeof *ctxt); 809 810 /* Start the authentication thread */ 811 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) { 812 error("PAM: failed create sockets: %s", strerror(errno)); 813 free(ctxt); 814 return (NULL); 815 } 816 ctxt->pam_psock = socks[0]; 817 ctxt->pam_csock = socks[1]; 818 result = pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt); 819 if (result != 0) { 820 error("PAM: failed to start authentication thread: %s", 821 strerror(result)); 822 close(socks[0]); 823 close(socks[1]); 824 free(ctxt); 825 return (NULL); 826 } 827 cleanup_ctxt = ctxt; 828 return (ctxt); 829 } 830 831 static int 832 sshpam_query(void *ctx, char **name, char **info, 833 u_int *num, char ***prompts, u_int **echo_on) 834 { 835 struct sshbuf *buffer; 836 struct pam_ctxt *ctxt = ctx; 837 size_t plen; 838 u_char type; 839 char *msg; 840 size_t len, mlen; 841 int r; 842 843 debug3("PAM: %s entering", __func__); 844 if ((buffer = sshbuf_new()) == NULL) 845 fatal("%s: sshbuf_new failed", __func__); 846 *name = xstrdup(""); 847 *info = xstrdup(""); 848 *prompts = xmalloc(sizeof(char *)); 849 **prompts = NULL; 850 plen = 0; 851 *echo_on = xmalloc(sizeof(u_int)); 852 while (ssh_msg_recv(ctxt->pam_psock, buffer) == 0) { 853 if ((r = sshbuf_get_u8(buffer, &type)) != 0 || 854 (r = sshbuf_get_cstring(buffer, &msg, &mlen)) != 0) 855 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 856 switch (type) { 857 case PAM_PROMPT_ECHO_ON: 858 case PAM_PROMPT_ECHO_OFF: 859 *num = 1; 860 len = plen + mlen + 1; 861 **prompts = xreallocarray(**prompts, 1, len); 862 strlcpy(**prompts + plen, msg, len - plen); 863 plen += mlen; 864 **echo_on = (type == PAM_PROMPT_ECHO_ON); 865 free(msg); 866 sshbuf_free(buffer); 867 return (0); 868 case PAM_ERROR_MSG: 869 case PAM_TEXT_INFO: 870 /* accumulate messages */ 871 len = plen + mlen + 2; 872 **prompts = xreallocarray(**prompts, 1, len); 873 strlcpy(**prompts + plen, msg, len - plen); 874 plen += mlen; 875 strlcat(**prompts + plen, "\n", len - plen); 876 plen++; 877 free(msg); 878 break; 879 case PAM_ACCT_EXPIRED: 880 case PAM_MAXTRIES: 881 if (type == PAM_ACCT_EXPIRED) 882 sshpam_account_status = 0; 883 if (type == PAM_MAXTRIES) 884 sshpam_set_maxtries_reached(1); 885 /* FALLTHROUGH */ 886 case PAM_AUTH_ERR: 887 debug3("PAM: %s", pam_strerror(sshpam_handle, type)); 888 if (**prompts != NULL && strlen(**prompts) != 0) { 889 free(*info); 890 *info = **prompts; 891 **prompts = NULL; 892 *num = 0; 893 **echo_on = 0; 894 ctxt->pam_done = -1; 895 free(msg); 896 sshbuf_free(buffer); 897 return 0; 898 } 899 /* FALLTHROUGH */ 900 case PAM_SUCCESS: 901 if (**prompts != NULL) { 902 /* drain any accumulated messages */ 903 debug("PAM: %s", **prompts); 904 if ((r = sshbuf_put(loginmsg, **prompts, 905 strlen(**prompts))) != 0) 906 fatal("%s: buffer error: %s", 907 __func__, ssh_err(r)); 908 free(**prompts); 909 **prompts = NULL; 910 } 911 if (type == PAM_SUCCESS) { 912 if (!sshpam_authctxt->valid || 913 (sshpam_authctxt->pw->pw_uid == 0 && 914 options.permit_root_login != PERMIT_YES)) 915 fatal("Internal error: PAM auth " 916 "succeeded when it should have " 917 "failed"); 918 import_environments(buffer); 919 *num = 0; 920 **echo_on = 0; 921 ctxt->pam_done = 1; 922 free(msg); 923 sshbuf_free(buffer); 924 return (0); 925 } 926 error("PAM: %s for %s%.100s from %.100s", msg, 927 sshpam_authctxt->valid ? "" : "illegal user ", 928 sshpam_authctxt->user, sshpam_rhost); 929 /* FALLTHROUGH */ 930 default: 931 *num = 0; 932 **echo_on = 0; 933 free(msg); 934 ctxt->pam_done = -1; 935 sshbuf_free(buffer); 936 return (-1); 937 } 938 } 939 sshbuf_free(buffer); 940 return (-1); 941 } 942 943 /* 944 * Returns a junk password of identical length to that the user supplied. 945 * Used to mitigate timing attacks against crypt(3)/PAM stacks that 946 * vary processing time in proportion to password length. 947 */ 948 static char * 949 fake_password(const char *wire_password) 950 { 951 const char junk[] = "\b\n\r\177INCORRECT"; 952 char *ret = NULL; 953 size_t i, l = wire_password != NULL ? strlen(wire_password) : 0; 954 955 if (l >= INT_MAX) 956 fatal("%s: password length too long: %zu", __func__, l); 957 958 ret = malloc(l + 1); 959 if (ret == NULL) 960 return NULL; 961 for (i = 0; i < l; i++) 962 ret[i] = junk[i % (sizeof(junk) - 1)]; 963 ret[i] = '\0'; 964 return ret; 965 } 966 967 /* XXX - see also comment in auth-chall.c:verify_response */ 968 static int 969 sshpam_respond(void *ctx, u_int num, char **resp) 970 { 971 struct sshbuf *buffer; 972 struct pam_ctxt *ctxt = ctx; 973 char *fake; 974 int r; 975 976 debug2("PAM: %s entering, %u responses", __func__, num); 977 switch (ctxt->pam_done) { 978 case 1: 979 sshpam_authenticated = 1; 980 return (0); 981 case 0: 982 break; 983 default: 984 return (-1); 985 } 986 if (num != 1) { 987 error("PAM: expected one response, got %u", num); 988 return (-1); 989 } 990 if ((buffer = sshbuf_new()) == NULL) 991 fatal("%s: sshbuf_new failed", __func__); 992 if (sshpam_authctxt->valid && 993 (sshpam_authctxt->pw->pw_uid != 0 || 994 options.permit_root_login == PERMIT_YES)) { 995 if ((r = sshbuf_put_cstring(buffer, *resp)) != 0) 996 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 997 } else { 998 fake = fake_password(*resp); 999 if ((r = sshbuf_put_cstring(buffer, fake)) != 0) 1000 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1001 free(fake); 1002 } 1003 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, buffer) == -1) { 1004 sshbuf_free(buffer); 1005 return (-1); 1006 } 1007 sshbuf_free(buffer); 1008 return (1); 1009 } 1010 1011 static void 1012 sshpam_free_ctx(void *ctxtp) 1013 { 1014 struct pam_ctxt *ctxt = ctxtp; 1015 1016 debug3("PAM: %s entering", __func__); 1017 sshpam_thread_cleanup(); 1018 free(ctxt); 1019 /* 1020 * We don't call sshpam_cleanup() here because we may need the PAM 1021 * handle at a later stage, e.g. when setting up a session. It's 1022 * still on the cleanup list, so pam_end() *will* be called before 1023 * the server process terminates. 1024 */ 1025 } 1026 1027 KbdintDevice sshpam_device = { 1028 "pam", 1029 sshpam_init_ctx, 1030 sshpam_query, 1031 sshpam_respond, 1032 sshpam_free_ctx 1033 }; 1034 1035 KbdintDevice mm_sshpam_device = { 1036 "pam", 1037 mm_sshpam_init_ctx, 1038 mm_sshpam_query, 1039 mm_sshpam_respond, 1040 mm_sshpam_free_ctx 1041 }; 1042 1043 /* 1044 * This replaces auth-pam.c 1045 */ 1046 void 1047 start_pam(struct ssh *ssh) 1048 { 1049 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1050 1051 if (!options.use_pam) 1052 fatal("PAM: initialisation requested when UsePAM=no"); 1053 1054 if (sshpam_init(ssh, authctxt) == -1) 1055 fatal("PAM: initialisation failed"); 1056 } 1057 1058 void 1059 finish_pam(void) 1060 { 1061 sshpam_cleanup(); 1062 } 1063 1064 1065 u_int 1066 do_pam_account(void) 1067 { 1068 debug("%s: called", __func__); 1069 if (sshpam_account_status != -1) 1070 return (sshpam_account_status); 1071 1072 expose_authinfo(__func__); 1073 1074 sshpam_err = pam_acct_mgmt(sshpam_handle, 0); 1075 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err, 1076 pam_strerror(sshpam_handle, sshpam_err)); 1077 1078 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) { 1079 sshpam_account_status = 0; 1080 return (sshpam_account_status); 1081 } 1082 1083 if (sshpam_err == PAM_NEW_AUTHTOK_REQD) 1084 sshpam_password_change_required(1); 1085 1086 sshpam_account_status = 1; 1087 return (sshpam_account_status); 1088 } 1089 1090 void 1091 do_pam_setcred(int init) 1092 { 1093 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1094 (const void *)&store_conv); 1095 if (sshpam_err != PAM_SUCCESS) 1096 fatal("PAM: failed to set PAM_CONV: %s", 1097 pam_strerror(sshpam_handle, sshpam_err)); 1098 if (init) { 1099 debug("PAM: establishing credentials"); 1100 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED); 1101 } else { 1102 debug("PAM: reinitializing credentials"); 1103 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED); 1104 } 1105 if (sshpam_err == PAM_SUCCESS) { 1106 sshpam_cred_established = 1; 1107 return; 1108 } 1109 if (sshpam_authenticated) 1110 fatal("PAM: pam_setcred(): %s", 1111 pam_strerror(sshpam_handle, sshpam_err)); 1112 else 1113 debug("PAM: pam_setcred(): %s", 1114 pam_strerror(sshpam_handle, sshpam_err)); 1115 } 1116 1117 static int 1118 sshpam_tty_conv(int n, sshpam_const struct pam_message **msg, 1119 struct pam_response **resp, void *data) 1120 { 1121 char input[PAM_MAX_MSG_SIZE]; 1122 struct pam_response *reply; 1123 int i; 1124 1125 debug3("PAM: %s called with %d messages", __func__, n); 1126 1127 *resp = NULL; 1128 1129 if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO)) 1130 return (PAM_CONV_ERR); 1131 1132 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1133 return (PAM_CONV_ERR); 1134 1135 for (i = 0; i < n; ++i) { 1136 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1137 case PAM_PROMPT_ECHO_OFF: 1138 reply[i].resp = 1139 read_passphrase(PAM_MSG_MEMBER(msg, i, msg), 1140 RP_ALLOW_STDIN); 1141 reply[i].resp_retcode = PAM_SUCCESS; 1142 break; 1143 case PAM_PROMPT_ECHO_ON: 1144 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1145 if (fgets(input, sizeof input, stdin) == NULL) 1146 input[0] = '\0'; 1147 if ((reply[i].resp = strdup(input)) == NULL) 1148 goto fail; 1149 reply[i].resp_retcode = PAM_SUCCESS; 1150 break; 1151 case PAM_ERROR_MSG: 1152 case PAM_TEXT_INFO: 1153 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1154 reply[i].resp_retcode = PAM_SUCCESS; 1155 break; 1156 default: 1157 goto fail; 1158 } 1159 } 1160 *resp = reply; 1161 return (PAM_SUCCESS); 1162 1163 fail: 1164 for(i = 0; i < n; i++) { 1165 free(reply[i].resp); 1166 } 1167 free(reply); 1168 return (PAM_CONV_ERR); 1169 } 1170 1171 static struct pam_conv tty_conv = { sshpam_tty_conv, NULL }; 1172 1173 /* 1174 * XXX this should be done in the authentication phase, but ssh1 doesn't 1175 * support that 1176 */ 1177 void 1178 do_pam_chauthtok(void) 1179 { 1180 if (use_privsep) 1181 fatal("Password expired (unable to change with privsep)"); 1182 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1183 (const void *)&tty_conv); 1184 if (sshpam_err != PAM_SUCCESS) 1185 fatal("PAM: failed to set PAM_CONV: %s", 1186 pam_strerror(sshpam_handle, sshpam_err)); 1187 debug("PAM: changing password"); 1188 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK); 1189 if (sshpam_err != PAM_SUCCESS) 1190 fatal("PAM: pam_chauthtok(): %s", 1191 pam_strerror(sshpam_handle, sshpam_err)); 1192 } 1193 1194 void 1195 do_pam_session(struct ssh *ssh) 1196 { 1197 debug3("PAM: opening session"); 1198 1199 expose_authinfo(__func__); 1200 1201 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1202 (const void *)&store_conv); 1203 if (sshpam_err != PAM_SUCCESS) 1204 fatal("PAM: failed to set PAM_CONV: %s", 1205 pam_strerror(sshpam_handle, sshpam_err)); 1206 sshpam_err = pam_open_session(sshpam_handle, 0); 1207 if (sshpam_err == PAM_SUCCESS) 1208 sshpam_session_open = 1; 1209 else { 1210 sshpam_session_open = 0; 1211 auth_restrict_session(ssh); 1212 error("PAM: pam_open_session(): %s", 1213 pam_strerror(sshpam_handle, sshpam_err)); 1214 } 1215 1216 } 1217 1218 int 1219 is_pam_session_open(void) 1220 { 1221 return sshpam_session_open; 1222 } 1223 1224 /* 1225 * Set a PAM environment string. We need to do this so that the session 1226 * modules can handle things like Kerberos/GSI credentials that appear 1227 * during the ssh authentication process. 1228 */ 1229 int 1230 do_pam_putenv(char *name, char *value) 1231 { 1232 int ret = 1; 1233 char *compound; 1234 size_t len; 1235 1236 len = strlen(name) + strlen(value) + 2; 1237 compound = xmalloc(len); 1238 1239 snprintf(compound, len, "%s=%s", name, value); 1240 ret = pam_putenv(sshpam_handle, compound); 1241 free(compound); 1242 1243 return (ret); 1244 } 1245 1246 char ** 1247 fetch_pam_child_environment(void) 1248 { 1249 return sshpam_env; 1250 } 1251 1252 char ** 1253 fetch_pam_environment(void) 1254 { 1255 return (pam_getenvlist(sshpam_handle)); 1256 } 1257 1258 void 1259 free_pam_environment(char **env) 1260 { 1261 char **envp; 1262 1263 if (env == NULL) 1264 return; 1265 1266 for (envp = env; *envp; envp++) 1267 free(*envp); 1268 free(env); 1269 } 1270 1271 /* 1272 * "Blind" conversation function for password authentication. Assumes that 1273 * echo-off prompts are for the password and stores messages for later 1274 * display. 1275 */ 1276 static int 1277 sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg, 1278 struct pam_response **resp, void *data) 1279 { 1280 struct pam_response *reply; 1281 int r, i; 1282 size_t len; 1283 1284 debug3("PAM: %s called with %d messages", __func__, n); 1285 1286 *resp = NULL; 1287 1288 if (n <= 0 || n > PAM_MAX_NUM_MSG) 1289 return (PAM_CONV_ERR); 1290 1291 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1292 return (PAM_CONV_ERR); 1293 1294 for (i = 0; i < n; ++i) { 1295 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1296 case PAM_PROMPT_ECHO_OFF: 1297 if (sshpam_password == NULL) 1298 goto fail; 1299 if ((reply[i].resp = strdup(sshpam_password)) == NULL) 1300 goto fail; 1301 reply[i].resp_retcode = PAM_SUCCESS; 1302 break; 1303 case PAM_ERROR_MSG: 1304 case PAM_TEXT_INFO: 1305 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 1306 if (len > 0) { 1307 if ((r = sshbuf_putf(loginmsg, "%s\n", 1308 PAM_MSG_MEMBER(msg, i, msg))) != 0) 1309 fatal("%s: buffer error: %s", 1310 __func__, ssh_err(r)); 1311 } 1312 if ((reply[i].resp = strdup("")) == NULL) 1313 goto fail; 1314 reply[i].resp_retcode = PAM_SUCCESS; 1315 break; 1316 default: 1317 goto fail; 1318 } 1319 } 1320 *resp = reply; 1321 return (PAM_SUCCESS); 1322 1323 fail: 1324 for(i = 0; i < n; i++) { 1325 free(reply[i].resp); 1326 } 1327 free(reply); 1328 return (PAM_CONV_ERR); 1329 } 1330 1331 static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL }; 1332 1333 /* 1334 * Attempt password authentication via PAM 1335 */ 1336 int 1337 sshpam_auth_passwd(Authctxt *authctxt, const char *password) 1338 { 1339 int flags = (options.permit_empty_passwd == 0 ? 1340 PAM_DISALLOW_NULL_AUTHTOK : 0); 1341 char *fake = NULL; 1342 1343 if (!options.use_pam || sshpam_handle == NULL) 1344 fatal("PAM: %s called when PAM disabled or failed to " 1345 "initialise.", __func__); 1346 1347 sshpam_password = password; 1348 sshpam_authctxt = authctxt; 1349 1350 /* 1351 * If the user logging in is invalid, or is root but is not permitted 1352 * by PermitRootLogin, use an invalid password to prevent leaking 1353 * information via timing (eg if the PAM config has a delay on fail). 1354 */ 1355 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 && 1356 options.permit_root_login != PERMIT_YES)) 1357 sshpam_password = fake = fake_password(password); 1358 1359 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1360 (const void *)&passwd_conv); 1361 if (sshpam_err != PAM_SUCCESS) 1362 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__, 1363 pam_strerror(sshpam_handle, sshpam_err)); 1364 1365 sshpam_err = pam_authenticate(sshpam_handle, flags); 1366 sshpam_password = NULL; 1367 free(fake); 1368 if (sshpam_err == PAM_MAXTRIES) 1369 sshpam_set_maxtries_reached(1); 1370 if (sshpam_err == PAM_SUCCESS && authctxt->valid) { 1371 debug("PAM: password authentication accepted for %.100s", 1372 authctxt->user); 1373 return 1; 1374 } else { 1375 debug("PAM: password authentication failed for %.100s: %s", 1376 authctxt->valid ? authctxt->user : "an illegal user", 1377 pam_strerror(sshpam_handle, sshpam_err)); 1378 return 0; 1379 } 1380 } 1381 1382 int 1383 sshpam_get_maxtries_reached(void) 1384 { 1385 return sshpam_maxtries_reached; 1386 } 1387 1388 void 1389 sshpam_set_maxtries_reached(int reached) 1390 { 1391 if (reached == 0 || sshpam_maxtries_reached) 1392 return; 1393 sshpam_maxtries_reached = 1; 1394 options.password_authentication = 0; 1395 options.kbd_interactive_authentication = 0; 1396 } 1397 #endif /* USE_PAM */ 1398