1/* $NetBSD: auth-pam.c,v 1.21 2023/10/25 20:19:57 christos Exp $ */ 2 3/*- 4 * Copyright (c) 2002 Networks Associates Technology, Inc. 5 * All rights reserved. 6 * 7 * This software was developed for the FreeBSD Project by ThinkSec AS and 8 * NAI Labs, the Security Research Division of Network Associates, Inc. 9 * under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), as part of the 10 * DARPA CHATS research program. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33/* 34 * Copyright (c) 2003,2004 Damien Miller <djm@mindrot.org> 35 * Copyright (c) 2003,2004 Darren Tucker <dtucker@zip.com.au> 36 * 37 * Permission to use, copy, modify, and distribute this software for any 38 * purpose with or without fee is hereby granted, provided that the above 39 * copyright notice and this permission notice appear in all copies. 40 * 41 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 42 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 43 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 44 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 45 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 46 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 47 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 48 */ 49 50/* Based on FreeBSD: src/crypto/openssh/auth2-pam-freebsd.c,v 1.11 2003/03/31 13:48:18 des */ 51 52#include "includes.h" 53/* 54 * NetBSD local changes 55 */ 56__RCSID("$NetBSD: auth-pam.c,v 1.21 2023/10/25 20:19:57 christos Exp $"); 57#define _LIB_PTHREAD_H 58#undef USE_POSIX_THREADS /* Not yet */ 59#define HAVE_SECURITY_PAM_APPL_H 60#define HAVE_PAM_GETENVLIST 61#define HAVE_PAM_PUTENV 62#define sshpam_const const /* LinuxPAM, OpenPAM */ 63#define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member) 64#define SSHD_PAM_SERVICE getprogname() 65/* end NetBSD local changes */ 66 67#include <sys/types.h> 68#include <sys/socket.h> 69#include <sys/stat.h> 70#include <sys/wait.h> 71 72#include <errno.h> 73#include <signal.h> 74#include <stdarg.h> 75#include <stdlib.h> 76#include <string.h> 77#include <unistd.h> 78#include <pwd.h> 79 80#ifdef USE_PAM 81#if defined(HAVE_SECURITY_PAM_APPL_H) 82#include <security/pam_appl.h> 83#elif defined (HAVE_PAM_PAM_APPL_H) 84#include <pam/pam_appl.h> 85#endif 86 87#if !defined(SSHD_PAM_SERVICE) 88extern char *__progname; 89# define SSHD_PAM_SERVICE __progname 90#endif 91 92#ifndef __NetBSD__ 93/* OpenGroup RFC86.0 and XSSO specify no "const" on arguments */ 94#ifdef PAM_SUN_CODEBASE 95# define sshpam_const /* Solaris, HP-UX, SunOS */ 96#else 97# define sshpam_const const /* LinuxPAM, OpenPAM, AIX */ 98#endif 99 100/* Ambiguity in spec: is it an array of pointers or a pointer to an array? */ 101#ifdef PAM_SUN_CODEBASE 102# define PAM_MSG_MEMBER(msg, n, member) ((*(msg))[(n)].member) 103#else 104# define PAM_MSG_MEMBER(msg, n, member) ((msg)[(n)]->member) 105#endif 106#endif 107 108#include "xmalloc.h" 109#include "sshbuf.h" 110#include "ssherr.h" 111#include "hostfile.h" 112#include "auth.h" 113#include "auth-pam.h" 114#include "canohost.h" 115#include "log.h" 116#include "msg.h" 117#include "packet.h" 118#include "misc.h" 119#include "servconf.h" 120#include "ssh2.h" 121#include "auth-options.h" 122#ifdef GSSAPI 123#include "ssh-gss.h" 124#endif 125#include "monitor_wrap.h" 126 127extern ServerOptions options; 128extern struct sshbuf *loginmsg; 129extern u_int utmp_len; 130 131/* so we don't silently change behaviour */ 132#ifdef USE_POSIX_THREADS 133# error "USE_POSIX_THREADS replaced by UNSUPPORTED_POSIX_THREADS_HACK" 134#endif 135 136/* 137 * Formerly known as USE_POSIX_THREADS, using this is completely unsupported 138 * and generally a bad idea. Use at own risk and do not expect support if 139 * this breaks. 140 */ 141#ifdef UNSUPPORTED_POSIX_THREADS_HACK 142#error "foo" 143#include <pthread.h> 144/* 145 * Avoid namespace clash when *not* using pthreads for systems *with* 146 * pthreads, which unconditionally define pthread_t via sys/types.h 147 * (e.g. Linux) 148 */ 149typedef pthread_t sp_pthread_t; 150#else 151typedef pid_t sp_pthread_t; 152#define pthread_exit fake_pthread_exit 153#define pthread_create fake_pthread_create 154#define pthread_cancel fake_pthread_cancel 155#define pthread_join fake_pthread_join 156#endif 157 158struct pam_ctxt { 159 sp_pthread_t pam_thread; 160 int pam_psock; 161 int pam_csock; 162 int pam_done; 163}; 164 165static void sshpam_free_ctx(void *); 166static struct pam_ctxt *cleanup_ctxt; 167 168#ifndef UNSUPPORTED_POSIX_THREADS_HACK 169/* 170 * Simulate threads with processes. 171 */ 172 173static int sshpam_thread_status = -1; 174static sshsig_t sshpam_oldsig; 175 176static void 177sshpam_sigchld_handler(int sig) 178{ 179 ssh_signal(SIGCHLD, SIG_DFL); 180 if (cleanup_ctxt == NULL) 181 return; /* handler called after PAM cleanup, shouldn't happen */ 182 if (waitpid(cleanup_ctxt->pam_thread, &sshpam_thread_status, WNOHANG) 183 <= 0) { 184 /* PAM thread has not exitted, privsep slave must have */ 185 kill(cleanup_ctxt->pam_thread, SIGTERM); 186 while (waitpid(cleanup_ctxt->pam_thread, 187 &sshpam_thread_status, 0) == -1) { 188 if (errno == EINTR) 189 continue; 190 return; 191 } 192 } 193 if (WIFSIGNALED(sshpam_thread_status) && 194 WTERMSIG(sshpam_thread_status) == SIGTERM) 195 return; /* terminated by pthread_cancel */ 196 if (!WIFEXITED(sshpam_thread_status)) 197 sigdie("PAM: authentication thread exited unexpectedly"); 198 if (WEXITSTATUS(sshpam_thread_status) != 0) 199 sigdie("PAM: authentication thread exited uncleanly"); 200} 201 202/* ARGSUSED */ 203__dead static void 204pthread_exit(void *value) 205{ 206 _exit(0); 207} 208 209/* ARGSUSED */ 210static int 211pthread_create(sp_pthread_t *thread, const void *attr, 212 void *(*thread_start)(void *), void *arg) 213{ 214 pid_t pid; 215 struct pam_ctxt *ctx = arg; 216 217 sshpam_thread_status = -1; 218 switch ((pid = fork())) { 219 case -1: 220 error("fork(): %s", strerror(errno)); 221 return errno; 222 case 0: 223 close(ctx->pam_psock); 224 ctx->pam_psock = -1; 225 thread_start(arg); 226 _exit(1); 227 default: 228 *thread = pid; 229 close(ctx->pam_csock); 230 ctx->pam_csock = -1; 231 sshpam_oldsig = ssh_signal(SIGCHLD, sshpam_sigchld_handler); 232 return (0); 233 } 234} 235 236static int 237pthread_cancel(sp_pthread_t thread) 238{ 239 ssh_signal(SIGCHLD, sshpam_oldsig); 240 return (kill(thread, SIGTERM)); 241} 242 243/* ARGSUSED */ 244static int 245pthread_join(sp_pthread_t thread, void **value) 246{ 247 int status; 248 249 if (sshpam_thread_status != -1) 250 return (sshpam_thread_status); 251 ssh_signal(SIGCHLD, sshpam_oldsig); 252 while (waitpid(thread, &status, 0) == -1) { 253 if (errno == EINTR) 254 continue; 255 fatal("%s: waitpid: %s", __func__, strerror(errno)); 256 } 257 return (status); 258} 259#endif 260 261 262static pam_handle_t *sshpam_handle = NULL; 263static int sshpam_err = 0; 264static int sshpam_authenticated = 0; 265static int sshpam_session_open = 0; 266static int sshpam_cred_established = 0; 267static int sshpam_account_status = -1; 268static int sshpam_maxtries_reached = 0; 269static char **sshpam_env = NULL; 270static Authctxt *sshpam_authctxt = NULL; 271static const char *sshpam_password = NULL; 272static char *sshpam_rhost = NULL; 273static char *sshpam_laddr = NULL; 274 275/* Some PAM implementations don't implement this */ 276#ifndef HAVE_PAM_GETENVLIST 277static char ** 278pam_getenvlist(pam_handle_t *pamh) 279{ 280 /* 281 * XXX - If necessary, we can still support environment passing 282 * for platforms without pam_getenvlist by searching for known 283 * env vars (e.g. KRB5CCNAME) from the PAM environment. 284 */ 285 return NULL; 286} 287#endif 288 289#ifndef HAVE_PAM_PUTENV 290static int 291pam_putenv(pam_handle_t *pamh, const char *name_value) 292{ 293 return PAM_SUCCESS; 294} 295#endif /* HAVE_PAM_PUTENV */ 296 297/* 298 * Some platforms, notably Solaris, do not enforce password complexity 299 * rules during pam_chauthtok() if the real uid of the calling process 300 * is 0, on the assumption that it's being called by "passwd" run by root. 301 * This wraps pam_chauthtok and sets/restore the real uid so PAM will do 302 * the right thing. 303 */ 304#ifdef SSHPAM_CHAUTHTOK_NEEDS_RUID 305static int 306sshpam_chauthtok_ruid(pam_handle_t *pamh, int flags) 307{ 308 int result; 309 310 if (sshpam_authctxt == NULL) 311 fatal("PAM: sshpam_authctxt not initialized"); 312 if (setreuid(sshpam_authctxt->pw->pw_uid, -1) == -1) 313 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 314 result = pam_chauthtok(pamh, flags); 315 if (setreuid(0, -1) == -1) 316 fatal("%s: setreuid failed: %s", __func__, strerror(errno)); 317 return result; 318} 319# define pam_chauthtok(a,b) (sshpam_chauthtok_ruid((a), (b))) 320#endif 321 322static void 323sshpam_password_change_required(int reqd) 324{ 325 extern struct sshauthopt *auth_opts; 326 static int saved_port, saved_agent, saved_x11; 327 328 debug3("%s %d", __func__, reqd); 329 if (sshpam_authctxt == NULL) 330 fatal("%s: PAM authctxt not initialized", __func__); 331 sshpam_authctxt->force_pwchange = reqd; 332 if (reqd) { 333 saved_port = auth_opts->permit_port_forwarding_flag; 334 saved_agent = auth_opts->permit_agent_forwarding_flag; 335 saved_x11 = auth_opts->permit_x11_forwarding_flag; 336 auth_opts->permit_port_forwarding_flag = 0; 337 auth_opts->permit_agent_forwarding_flag = 0; 338 auth_opts->permit_x11_forwarding_flag = 0; 339 } else { 340 if (saved_port) 341 auth_opts->permit_port_forwarding_flag = saved_port; 342 if (saved_agent) 343 auth_opts->permit_agent_forwarding_flag = saved_agent; 344 if (saved_x11) 345 auth_opts->permit_x11_forwarding_flag = saved_x11; 346 } 347} 348 349/* Import regular and PAM environment from subprocess */ 350static void 351import_environments(struct sshbuf *b) 352{ 353 char *env; 354 u_int n, i, num_env; 355 int r; 356 357 debug3("PAM: %s entering", __func__); 358 359#ifndef UNSUPPORTED_POSIX_THREADS_HACK 360 /* Import variables set by do_pam_account */ 361 if ((r = sshbuf_get_u32(b, &n)) != 0) 362 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 363 if (n > INT_MAX) 364 fatal("%s: invalid PAM account status %u", __func__, n); 365 sshpam_account_status = (int)n; 366 if ((r = sshbuf_get_u32(b, &n)) != 0) 367 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 368 sshpam_password_change_required(n != 0); 369 370 /* Import environment from subprocess */ 371 if ((r = sshbuf_get_u32(b, &num_env)) != 0) 372 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 373 if (num_env > 1024) { 374 fatal_f("received %u environment variables, expected <= 1024", 375 num_env); 376 } 377 sshpam_env = xcalloc(num_env + 1, sizeof(*sshpam_env)); 378 debug3("PAM: num env strings %u", num_env); 379 for(i = 0; i < num_env; i++) { 380 if ((r = sshbuf_get_cstring(b, &(sshpam_env[i]), NULL)) != 0) 381 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 382 } 383 sshpam_env[num_env] = NULL; 384 385 /* Import PAM environment from subprocess */ 386 if ((r = sshbuf_get_u32(b, &num_env)) != 0) 387 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 388 if (num_env > 1024) { 389 fatal_f("received %u PAM env variables, expected <= 1024", 390 num_env); 391 } 392 debug("PAM: num PAM env strings %u", num_env); 393 for (i = 0; i < num_env; i++) { 394 if ((r = sshbuf_get_cstring(b, &env, NULL)) != 0) 395 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 396#ifdef HAVE_PAM_PUTENV 397 /* Errors are not fatal here */ 398 if ((r = pam_putenv(sshpam_handle, env)) != PAM_SUCCESS) { 399 error("PAM: pam_putenv: %s", 400 pam_strerror(sshpam_handle, r)); 401 } 402#endif 403 /* 404 * XXX this possibly leaks env because it is not documented 405 * what pam_putenv() does with it. Does it copy it? Does it 406 * take ownweship? We don't know, so it's safest just to leak. 407 */ 408 } 409#endif 410} 411 412/* 413 * Conversation function for authentication thread. 414 */ 415static int 416sshpam_thread_conv(int n, sshpam_const struct pam_message **msg, 417 struct pam_response **resp, void *data) 418{ 419 struct sshbuf *buffer; 420 struct pam_ctxt *ctxt; 421 struct pam_response *reply; 422 int r, i; 423 u_char status; 424 425 debug3("PAM: %s entering, %d messages", __func__, n); 426 *resp = NULL; 427 428 if (data == NULL) { 429 error("PAM: conversation function passed a null context"); 430 return (PAM_CONV_ERR); 431 } 432 ctxt = data; 433 if (n <= 0 || n > PAM_MAX_NUM_MSG) 434 return (PAM_CONV_ERR); 435 436 if ((reply = calloc(n, sizeof(*reply))) == NULL) 437 return PAM_CONV_ERR; 438 if ((buffer = sshbuf_new()) == NULL) { 439 free(reply); 440 return PAM_CONV_ERR; 441 } 442 443 for (i = 0; i < n; ++i) { 444 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 445 case PAM_PROMPT_ECHO_OFF: 446 case PAM_PROMPT_ECHO_ON: 447 if ((r = sshbuf_put_cstring(buffer, 448 PAM_MSG_MEMBER(msg, i, msg))) != 0) 449 fatal("%s: buffer error: %s", 450 __func__, ssh_err(r)); 451 if (ssh_msg_send(ctxt->pam_csock, 452 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1) 453 goto fail; 454 455 if (ssh_msg_recv(ctxt->pam_csock, buffer) == -1) 456 goto fail; 457 if ((r = sshbuf_get_u8(buffer, &status)) != 0) 458 fatal("%s: buffer error: %s", 459 __func__, ssh_err(r)); 460 if (status != PAM_AUTHTOK) 461 goto fail; 462 if ((r = sshbuf_get_cstring(buffer, 463 &reply[i].resp, NULL)) != 0) 464 fatal("%s: buffer error: %s", 465 __func__, ssh_err(r)); 466 break; 467 case PAM_ERROR_MSG: 468 case PAM_TEXT_INFO: 469 if ((r = sshbuf_put_cstring(buffer, 470 PAM_MSG_MEMBER(msg, i, msg))) != 0) 471 fatal("%s: buffer error: %s", 472 __func__, ssh_err(r)); 473 if (ssh_msg_send(ctxt->pam_csock, 474 PAM_MSG_MEMBER(msg, i, msg_style), buffer) == -1) 475 goto fail; 476 break; 477 default: 478 goto fail; 479 } 480 sshbuf_reset(buffer); 481 } 482 sshbuf_free(buffer); 483 *resp = reply; 484 return (PAM_SUCCESS); 485 486 fail: 487 for(i = 0; i < n; i++) { 488 free(reply[i].resp); 489 } 490 free(reply); 491 sshbuf_free(buffer); 492 return (PAM_CONV_ERR); 493} 494 495/* 496 * Authentication thread. 497 */ 498static void * 499sshpam_thread(void *ctxtp) 500{ 501 struct pam_ctxt *ctxt = ctxtp; 502 struct sshbuf *buffer = NULL; 503 struct pam_conv sshpam_conv; 504 int r, flags = (options.permit_empty_passwd == 0 ? 505 PAM_DISALLOW_NULL_AUTHTOK : 0); 506#ifndef UNSUPPORTED_POSIX_THREADS_HACK 507 extern char **environ; 508 char **env_from_pam; 509 u_int i; 510 const char *pam_user; 511 const char **ptr_pam_user = &pam_user; 512 char *tz = getenv("TZ"); 513 514 sshpam_err = pam_get_item(sshpam_handle, PAM_USER, 515 (sshpam_const void **)ptr_pam_user); 516 if (sshpam_err != PAM_SUCCESS) 517 goto auth_fail; 518 519 environ[0] = NULL; 520 if (tz != NULL) 521 if (setenv("TZ", tz, 1) == -1) 522 error("PAM: could not set TZ environment: %s", 523 strerror(errno)); 524 525 if (sshpam_authctxt != NULL) { 526 setproctitle("%s [pam]", 527 sshpam_authctxt->valid ? pam_user : "unknown"); 528 } 529#endif 530 531 sshpam_conv.conv = sshpam_thread_conv; 532 sshpam_conv.appdata_ptr = ctxt; 533 534 if (sshpam_authctxt == NULL) 535 fatal("%s: PAM authctxt not initialized", __func__); 536 537 if ((buffer = sshbuf_new()) == NULL) 538 fatal("%s: sshbuf_new failed", __func__); 539 540 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 541 (const void *)&sshpam_conv); 542 if (sshpam_err != PAM_SUCCESS) 543 goto auth_fail; 544 sshpam_err = pam_authenticate(sshpam_handle, flags); 545 if (sshpam_err == PAM_MAXTRIES) 546 sshpam_set_maxtries_reached(1); 547 if (sshpam_err != PAM_SUCCESS) 548 goto auth_fail; 549 550 if (!do_pam_account()) { 551 sshpam_err = PAM_ACCT_EXPIRED; 552 goto auth_fail; 553 } 554 if (sshpam_authctxt->force_pwchange) { 555 sshpam_err = pam_chauthtok(sshpam_handle, 556 PAM_CHANGE_EXPIRED_AUTHTOK); 557 if (sshpam_err != PAM_SUCCESS) 558 goto auth_fail; 559 sshpam_password_change_required(0); 560 } 561 562 if ((r = sshbuf_put_cstring(buffer, "OK")) != 0) 563 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 564 565#ifndef UNSUPPORTED_POSIX_THREADS_HACK 566 /* Export variables set by do_pam_account */ 567 if ((r = sshbuf_put_u32(buffer, sshpam_account_status)) != 0 || 568 (r = sshbuf_put_u32(buffer, sshpam_authctxt->force_pwchange)) != 0) 569 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 570 571 /* Export any environment strings set in child */ 572 for (i = 0; environ[i] != NULL; i++) { 573 /* Count */ 574 if (i > INT_MAX) 575 fatal("%s: too many environment strings", __func__); 576 } 577 if ((r = sshbuf_put_u32(buffer, i)) != 0) 578 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 579 for (i = 0; environ[i] != NULL; i++) { 580 if ((r = sshbuf_put_cstring(buffer, environ[i])) != 0) 581 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 582 } 583 /* Export any environment strings set by PAM in child */ 584 env_from_pam = pam_getenvlist(sshpam_handle); 585 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) { 586 /* Count */ 587 if (i > INT_MAX) 588 fatal("%s: too many PAM environment strings", __func__); 589 } 590 if ((r = sshbuf_put_u32(buffer, i)) != 0) 591 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 592 for (i = 0; env_from_pam != NULL && env_from_pam[i] != NULL; i++) { 593 if ((r = sshbuf_put_cstring(buffer, env_from_pam[i])) != 0) 594 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 595 } 596#endif /* UNSUPPORTED_POSIX_THREADS_HACK */ 597 598 /* XXX - can't do much about an error here */ 599 ssh_msg_send(ctxt->pam_csock, sshpam_err, buffer); 600 sshbuf_free(buffer); 601 pthread_exit(NULL); 602 603 auth_fail: 604 if ((r = sshbuf_put_cstring(buffer, 605 pam_strerror(sshpam_handle, sshpam_err))) != 0) 606 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 607 /* XXX - can't do much about an error here */ 608 if (sshpam_err == PAM_ACCT_EXPIRED) 609 ssh_msg_send(ctxt->pam_csock, PAM_ACCT_EXPIRED, buffer); 610 else if (sshpam_maxtries_reached) 611 ssh_msg_send(ctxt->pam_csock, PAM_MAXTRIES, buffer); 612 else 613 ssh_msg_send(ctxt->pam_csock, PAM_AUTH_ERR, buffer); 614 sshbuf_free(buffer); 615 pthread_exit(NULL); 616 617 return (NULL); /* Avoid warning for non-pthread case */ 618} 619 620void 621sshpam_thread_cleanup(void) 622{ 623 struct pam_ctxt *ctxt = cleanup_ctxt; 624 625 debug3("PAM: %s entering", __func__); 626 if (ctxt != NULL && ctxt->pam_thread != 0) { 627 pthread_cancel(ctxt->pam_thread); 628 pthread_join(ctxt->pam_thread, NULL); 629 close(ctxt->pam_psock); 630 close(ctxt->pam_csock); 631 memset(ctxt, 0, sizeof(*ctxt)); 632 cleanup_ctxt = NULL; 633 } 634} 635 636static int 637sshpam_null_conv(int n, sshpam_const struct pam_message **msg, 638 struct pam_response **resp, void *data) 639{ 640 debug3("PAM: %s entering, %d messages", __func__, n); 641 return (PAM_CONV_ERR); 642} 643 644static struct pam_conv null_conv = { sshpam_null_conv, NULL }; 645 646static int 647sshpam_store_conv(int n, sshpam_const struct pam_message **msg, 648 struct pam_response **resp, void *data) 649{ 650 struct pam_response *reply; 651 int r, i; 652 653 debug3("PAM: %s called with %d messages", __func__, n); 654 *resp = NULL; 655 656 if (n <= 0 || n > PAM_MAX_NUM_MSG) 657 return (PAM_CONV_ERR); 658 659 if ((reply = calloc(n, sizeof(*reply))) == NULL) 660 return (PAM_CONV_ERR); 661 662 for (i = 0; i < n; ++i) { 663 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 664 case PAM_ERROR_MSG: 665 case PAM_TEXT_INFO: 666 if ((r = sshbuf_putf(loginmsg, "%s\n", 667 PAM_MSG_MEMBER(msg, i, msg))) != 0) 668 fatal("%s: buffer error: %s", 669 __func__, ssh_err(r)); 670 reply[i].resp_retcode = PAM_SUCCESS; 671 break; 672 default: 673 goto fail; 674 } 675 } 676 *resp = reply; 677 return (PAM_SUCCESS); 678 679 fail: 680 for(i = 0; i < n; i++) { 681 free(reply[i].resp); 682 } 683 free(reply); 684 return (PAM_CONV_ERR); 685} 686 687static struct pam_conv store_conv = { sshpam_store_conv, NULL }; 688 689void 690sshpam_cleanup(void) 691{ 692 if (sshpam_handle == NULL || (use_privsep && !mm_is_monitor())) 693 return; 694 debug("PAM: cleanup"); 695 pam_set_item(sshpam_handle, PAM_CONV, (const void *)&null_conv); 696 if (sshpam_session_open) { 697 debug("PAM: closing session"); 698 pam_close_session(sshpam_handle, PAM_SILENT); 699 sshpam_session_open = 0; 700 } 701 if (sshpam_cred_established) { 702 debug("PAM: deleting credentials"); 703 pam_setcred(sshpam_handle, PAM_DELETE_CRED); 704 sshpam_cred_established = 0; 705 } 706 sshpam_authenticated = 0; 707 pam_end(sshpam_handle, sshpam_err); 708 sshpam_handle = NULL; 709} 710 711static int 712sshpam_init(struct ssh *ssh, Authctxt *authctxt) 713{ 714 const char *pam_user, *user = authctxt->user; 715 const char **ptr_pam_user = &pam_user; 716 int r; 717 718#if defined(PAM_SUN_CODEBASE) && defined(PAM_MAX_RESP_SIZE) 719 /* Protect buggy PAM implementations from excessively long usernames */ 720 if (strlen(user) >= PAM_MAX_RESP_SIZE) 721 fatal("Username too long from %s port %d", 722 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh)); 723#endif 724 725 if (sshpam_handle == NULL) { 726 if (ssh == NULL) { 727 fatal("%s: called initially with no " 728 "packet context", __func__); 729 } 730 } if (sshpam_handle != NULL) { 731 /* We already have a PAM context; check if the user matches */ 732 sshpam_err = pam_get_item(sshpam_handle, 733 PAM_USER, (sshpam_const void **)ptr_pam_user); 734 if (sshpam_err == PAM_SUCCESS && strcmp(user, pam_user) == 0) 735 return (0); 736 pam_end(sshpam_handle, sshpam_err); 737 sshpam_handle = NULL; 738 } 739 debug("PAM: initializing for \"%s\"", user); 740 sshpam_err = 741 pam_start(SSHD_PAM_SERVICE, user, &store_conv, &sshpam_handle); 742 sshpam_authctxt = authctxt; 743 744 if (sshpam_err != PAM_SUCCESS) { 745 pam_end(sshpam_handle, sshpam_err); 746 sshpam_handle = NULL; 747 return (-1); 748 } 749 750 if (ssh != NULL && sshpam_rhost == NULL) { 751 /* 752 * We need to cache these as we don't have packet context 753 * during the kbdint flow. 754 */ 755 sshpam_rhost = xstrdup(auth_get_canonical_hostname(ssh, 756 options.use_dns)); 757 sshpam_laddr = get_local_ipaddr( 758 ssh_packet_get_connection_in(ssh)); 759 } 760 if (sshpam_rhost != NULL) { 761 debug("PAM: setting PAM_RHOST to \"%s\"", sshpam_rhost); 762 sshpam_err = pam_set_item(sshpam_handle, PAM_RHOST, 763 sshpam_rhost); 764 if (sshpam_err != PAM_SUCCESS) { 765 pam_end(sshpam_handle, sshpam_err); 766 sshpam_handle = NULL; 767 return (-1); 768 } 769 } 770 if (ssh != NULL && sshpam_laddr != NULL) { 771 char *conninfo; 772 773 /* Put SSH_CONNECTION in the PAM environment too */ 774 xasprintf(&conninfo, "SSH_CONNECTION=%.50s %d %.50s %d", 775 ssh_remote_ipaddr(ssh), ssh_remote_port(ssh), 776 sshpam_laddr, ssh_local_port(ssh)); 777 if ((r = pam_putenv(sshpam_handle, conninfo)) != PAM_SUCCESS) 778 logit("pam_putenv: %s", pam_strerror(sshpam_handle, r)); 779 free(conninfo); 780 } 781 782#ifdef PAM_TTY_KLUDGE 783 /* 784 * Some silly PAM modules (e.g. pam_time) require a TTY to operate. 785 * sshd doesn't set the tty until too late in the auth process and 786 * may not even set one (for tty-less connections) 787 */ 788 debug("PAM: setting PAM_TTY to \"ssh\""); 789 sshpam_err = pam_set_item(sshpam_handle, PAM_TTY, "ssh"); 790 if (sshpam_err != PAM_SUCCESS) { 791 pam_end(sshpam_handle, sshpam_err); 792 sshpam_handle = NULL; 793 return (-1); 794 } 795#endif 796 return (0); 797} 798 799static void 800expose_authinfo(const char *caller) 801{ 802 char *auth_info; 803 804 /* 805 * Expose authentication information to PAM. 806 * The environment variable is versioned. Please increment the 807 * version suffix if the format of session_info changes. 808 */ 809 if (sshpam_authctxt->session_info == NULL) 810 auth_info = xstrdup(""); 811 else if ((auth_info = sshbuf_dup_string( 812 sshpam_authctxt->session_info)) == NULL) 813 fatal("%s: sshbuf_dup_string failed", __func__); 814 815 debug2("%s: auth information in SSH_AUTH_INFO_0", caller); 816 do_pam_putenv("SSH_AUTH_INFO_0", auth_info); 817 free(auth_info); 818} 819 820static void * 821sshpam_init_ctx(Authctxt *authctxt) 822{ 823 struct pam_ctxt *ctxt; 824 int result, socks[2]; 825 826 debug3("PAM: %s entering", __func__); 827 /* 828 * Refuse to start if we don't have PAM enabled or do_pam_account 829 * has previously failed. 830 */ 831 if (!options.use_pam || sshpam_account_status == 0) 832 return NULL; 833 834 /* Initialize PAM */ 835 if (sshpam_init(NULL, authctxt) == -1) { 836 error("PAM: initialization failed"); 837 return (NULL); 838 } 839 840 expose_authinfo(__func__); 841 ctxt = xcalloc(1, sizeof *ctxt); 842 843 /* Start the authentication thread */ 844 if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) { 845 error("PAM: failed create sockets: %s", strerror(errno)); 846 free(ctxt); 847 return (NULL); 848 } 849 ctxt->pam_psock = socks[0]; 850 ctxt->pam_csock = socks[1]; 851 result = pthread_create(&ctxt->pam_thread, NULL, sshpam_thread, ctxt); 852 if (result != 0) { 853 error("PAM: failed to start authentication thread: %s", 854 strerror(result)); 855 close(socks[0]); 856 close(socks[1]); 857 free(ctxt); 858 return (NULL); 859 } 860 cleanup_ctxt = ctxt; 861 return (ctxt); 862} 863 864static int 865sshpam_query(void *ctx, char **name, char **info, 866 u_int *num, char ***prompts, u_int **echo_on) 867{ 868 struct sshbuf *buffer; 869 struct pam_ctxt *ctxt = ctx; 870 size_t plen; 871 u_char type; 872 char *msg; 873 size_t len, mlen, nmesg = 0; 874 int r; 875 876 debug3("PAM: %s entering", __func__); 877 if ((buffer = sshbuf_new()) == NULL) 878 fatal("%s: sshbuf_new failed", __func__); 879 *name = xstrdup(""); 880 *info = xstrdup(""); 881 *prompts = xmalloc(sizeof(char *)); 882 **prompts = NULL; 883 plen = 0; 884 *echo_on = xmalloc(sizeof(u_int)); 885 while (ssh_msg_recv(ctxt->pam_psock, buffer) == 0) { 886 if (++nmesg > PAM_MAX_NUM_MSG) 887 fatal_f("too many query messages"); 888 if ((r = sshbuf_get_u8(buffer, &type)) != 0 || 889 (r = sshbuf_get_cstring(buffer, &msg, &mlen)) != 0) 890 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 891 switch (type) { 892 case PAM_PROMPT_ECHO_ON: 893 case PAM_PROMPT_ECHO_OFF: 894 *num = 1; 895 len = plen + mlen + 1; 896 **prompts = xreallocarray(**prompts, 1, len); 897 strlcpy(**prompts + plen, msg, len - plen); 898 plen += mlen; 899 **echo_on = (type == PAM_PROMPT_ECHO_ON); 900 free(msg); 901 sshbuf_free(buffer); 902 return (0); 903 case PAM_ERROR_MSG: 904 case PAM_TEXT_INFO: 905 /* accumulate messages */ 906 len = plen + mlen + 2; 907 **prompts = xreallocarray(**prompts, 1, len); 908 strlcpy(**prompts + plen, msg, len - plen); 909 plen += mlen; 910 strlcat(**prompts + plen, "\n", len - plen); 911 plen++; 912 free(msg); 913 break; 914 case PAM_ACCT_EXPIRED: 915 case PAM_MAXTRIES: 916 if (type == PAM_ACCT_EXPIRED) 917 sshpam_account_status = 0; 918 if (type == PAM_MAXTRIES) 919 sshpam_set_maxtries_reached(1); 920 /* FALLTHROUGH */ 921 case PAM_AUTH_ERR: 922 debug3("PAM: %s", pam_strerror(sshpam_handle, type)); 923 if (**prompts != NULL && strlen(**prompts) != 0) { 924 free(*info); 925 *info = **prompts; 926 **prompts = NULL; 927 *num = 0; 928 **echo_on = 0; 929 ctxt->pam_done = -1; 930 free(msg); 931 sshbuf_free(buffer); 932 return 0; 933 } 934 /* FALLTHROUGH */ 935 case PAM_SUCCESS: 936 if (**prompts != NULL) { 937 /* drain any accumulated messages */ 938 debug("PAM: %s", **prompts); 939 if ((r = sshbuf_put(loginmsg, **prompts, 940 strlen(**prompts))) != 0) 941 fatal("%s: buffer error: %s", 942 __func__, ssh_err(r)); 943 free(**prompts); 944 **prompts = NULL; 945 } 946 if (type == PAM_SUCCESS) { 947 if (!sshpam_authctxt->valid || 948 (sshpam_authctxt->pw->pw_uid == 0 && 949 options.permit_root_login != PERMIT_YES)) 950 fatal("Internal error: PAM auth " 951 "succeeded when it should have " 952 "failed"); 953 import_environments(buffer); 954 *num = 0; 955 **echo_on = 0; 956 ctxt->pam_done = 1; 957 free(msg); 958 sshbuf_free(buffer); 959 return (0); 960 } 961 error("PAM: %s for %s%.100s from %.100s", msg, 962 sshpam_authctxt->valid ? "" : "illegal user ", 963 sshpam_authctxt->user, sshpam_rhost); 964 /* FALLTHROUGH */ 965 default: 966 *num = 0; 967 **echo_on = 0; 968 free(msg); 969 ctxt->pam_done = -1; 970 sshbuf_free(buffer); 971 return (-1); 972 } 973 } 974 sshbuf_free(buffer); 975 return (-1); 976} 977 978/* 979 * Returns a junk password of identical length to that the user supplied. 980 * Used to mitigate timing attacks against crypt(3)/PAM stacks that 981 * vary processing time in proportion to password length. 982 */ 983static char * 984fake_password(const char *wire_password) 985{ 986 const char junk[] = "\b\n\r\177INCORRECT"; 987 char *ret = NULL; 988 size_t i, l = wire_password != NULL ? strlen(wire_password) : 0; 989 990 if (l >= INT_MAX) 991 fatal("%s: password length too long: %zu", __func__, l); 992 993 ret = malloc(l + 1); 994 if (ret == NULL) 995 return NULL; 996 for (i = 0; i < l; i++) 997 ret[i] = junk[i % (sizeof(junk) - 1)]; 998 ret[i] = '\0'; 999 return ret; 1000} 1001 1002/* XXX - see also comment in auth-chall.c:verify_response */ 1003static int 1004sshpam_respond(void *ctx, u_int num, char **resp) 1005{ 1006 struct sshbuf *buffer; 1007 struct pam_ctxt *ctxt = ctx; 1008 char *fake; 1009 int r; 1010 1011 debug2("PAM: %s entering, %u responses", __func__, num); 1012 switch (ctxt->pam_done) { 1013 case 1: 1014 sshpam_authenticated = 1; 1015 return (0); 1016 case 0: 1017 break; 1018 default: 1019 return (-1); 1020 } 1021 if (num != 1) { 1022 error("PAM: expected one response, got %u", num); 1023 return (-1); 1024 } 1025 if ((buffer = sshbuf_new()) == NULL) 1026 fatal("%s: sshbuf_new failed", __func__); 1027 if (sshpam_authctxt->valid && 1028 (sshpam_authctxt->pw->pw_uid != 0 || 1029 options.permit_root_login == PERMIT_YES)) { 1030 if ((r = sshbuf_put_cstring(buffer, *resp)) != 0) 1031 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1032 } else { 1033 fake = fake_password(*resp); 1034 if ((r = sshbuf_put_cstring(buffer, fake)) != 0) 1035 fatal("%s: buffer error: %s", __func__, ssh_err(r)); 1036 free(fake); 1037 } 1038 if (ssh_msg_send(ctxt->pam_psock, PAM_AUTHTOK, buffer) == -1) { 1039 sshbuf_free(buffer); 1040 return (-1); 1041 } 1042 sshbuf_free(buffer); 1043 return (1); 1044} 1045 1046static void 1047sshpam_free_ctx(void *ctxtp) 1048{ 1049 struct pam_ctxt *ctxt = ctxtp; 1050 1051 debug3("PAM: %s entering", __func__); 1052 sshpam_thread_cleanup(); 1053 free(ctxt); 1054 /* 1055 * We don't call sshpam_cleanup() here because we may need the PAM 1056 * handle at a later stage, e.g. when setting up a session. It's 1057 * still on the cleanup list, so pam_end() *will* be called before 1058 * the server process terminates. 1059 */ 1060} 1061 1062KbdintDevice sshpam_device = { 1063 "pam", 1064 sshpam_init_ctx, 1065 sshpam_query, 1066 sshpam_respond, 1067 sshpam_free_ctx 1068}; 1069 1070KbdintDevice mm_sshpam_device = { 1071 "pam", 1072 mm_sshpam_init_ctx, 1073 mm_sshpam_query, 1074 mm_sshpam_respond, 1075 mm_sshpam_free_ctx 1076}; 1077 1078/* 1079 * This replaces auth-pam.c 1080 */ 1081void 1082start_pam(struct ssh *ssh) 1083{ 1084 Authctxt *authctxt = (Authctxt *)ssh->authctxt; 1085 1086 if (!options.use_pam) 1087 fatal("PAM: initialisation requested when UsePAM=no"); 1088 1089 if (sshpam_init(ssh, authctxt) == -1) 1090 fatal("PAM: initialisation failed"); 1091} 1092 1093void 1094finish_pam(void) 1095{ 1096 sshpam_cleanup(); 1097} 1098 1099 1100u_int 1101do_pam_account(void) 1102{ 1103 debug("%s: called", __func__); 1104 if (sshpam_account_status != -1) 1105 return (sshpam_account_status); 1106 1107 expose_authinfo(__func__); 1108 1109 sshpam_err = pam_acct_mgmt(sshpam_handle, 0); 1110 debug3("PAM: %s pam_acct_mgmt = %d (%s)", __func__, sshpam_err, 1111 pam_strerror(sshpam_handle, sshpam_err)); 1112 1113 if (sshpam_err != PAM_SUCCESS && sshpam_err != PAM_NEW_AUTHTOK_REQD) { 1114 sshpam_account_status = 0; 1115 return (sshpam_account_status); 1116 } 1117 1118 if (sshpam_err == PAM_NEW_AUTHTOK_REQD) 1119 sshpam_password_change_required(1); 1120 1121 sshpam_account_status = 1; 1122 return (sshpam_account_status); 1123} 1124 1125void 1126do_pam_setcred(int init) 1127{ 1128 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1129 (const void *)&store_conv); 1130 if (sshpam_err != PAM_SUCCESS) 1131 fatal("PAM: failed to set PAM_CONV: %s", 1132 pam_strerror(sshpam_handle, sshpam_err)); 1133 if (init) { 1134 debug("PAM: establishing credentials"); 1135 sshpam_err = pam_setcred(sshpam_handle, PAM_ESTABLISH_CRED); 1136 } else { 1137 debug("PAM: reinitializing credentials"); 1138 sshpam_err = pam_setcred(sshpam_handle, PAM_REINITIALIZE_CRED); 1139 } 1140 if (sshpam_err == PAM_SUCCESS) { 1141 sshpam_cred_established = 1; 1142 return; 1143 } 1144 if (sshpam_authenticated) 1145 fatal("PAM: pam_setcred(): %s", 1146 pam_strerror(sshpam_handle, sshpam_err)); 1147 else 1148 debug("PAM: pam_setcred(): %s", 1149 pam_strerror(sshpam_handle, sshpam_err)); 1150} 1151 1152static int 1153sshpam_tty_conv(int n, sshpam_const struct pam_message **msg, 1154 struct pam_response **resp, void *data) 1155{ 1156 char input[PAM_MAX_MSG_SIZE]; 1157 struct pam_response *reply; 1158 int i; 1159 1160 debug3("PAM: %s called with %d messages", __func__, n); 1161 1162 *resp = NULL; 1163 1164 if (n <= 0 || n > PAM_MAX_NUM_MSG || !isatty(STDIN_FILENO)) 1165 return (PAM_CONV_ERR); 1166 1167 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1168 return (PAM_CONV_ERR); 1169 1170 for (i = 0; i < n; ++i) { 1171 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1172 case PAM_PROMPT_ECHO_OFF: 1173 reply[i].resp = 1174 read_passphrase(PAM_MSG_MEMBER(msg, i, msg), 1175 RP_ALLOW_STDIN); 1176 reply[i].resp_retcode = PAM_SUCCESS; 1177 break; 1178 case PAM_PROMPT_ECHO_ON: 1179 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1180 if (fgets(input, sizeof input, stdin) == NULL) 1181 input[0] = '\0'; 1182 if ((reply[i].resp = strdup(input)) == NULL) 1183 goto fail; 1184 reply[i].resp_retcode = PAM_SUCCESS; 1185 break; 1186 case PAM_ERROR_MSG: 1187 case PAM_TEXT_INFO: 1188 fprintf(stderr, "%s\n", PAM_MSG_MEMBER(msg, i, msg)); 1189 reply[i].resp_retcode = PAM_SUCCESS; 1190 break; 1191 default: 1192 goto fail; 1193 } 1194 } 1195 *resp = reply; 1196 return (PAM_SUCCESS); 1197 1198 fail: 1199 for(i = 0; i < n; i++) { 1200 free(reply[i].resp); 1201 } 1202 free(reply); 1203 return (PAM_CONV_ERR); 1204} 1205 1206static struct pam_conv tty_conv = { sshpam_tty_conv, NULL }; 1207 1208/* 1209 * XXX this should be done in the authentication phase, but ssh1 doesn't 1210 * support that 1211 */ 1212void 1213do_pam_chauthtok(void) 1214{ 1215 if (use_privsep) 1216 fatal("Password expired (unable to change with privsep)"); 1217 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1218 (const void *)&tty_conv); 1219 if (sshpam_err != PAM_SUCCESS) 1220 fatal("PAM: failed to set PAM_CONV: %s", 1221 pam_strerror(sshpam_handle, sshpam_err)); 1222 debug("PAM: changing password"); 1223 sshpam_err = pam_chauthtok(sshpam_handle, PAM_CHANGE_EXPIRED_AUTHTOK); 1224 if (sshpam_err != PAM_SUCCESS) 1225 fatal("PAM: pam_chauthtok(): %s", 1226 pam_strerror(sshpam_handle, sshpam_err)); 1227} 1228 1229void 1230do_pam_session(struct ssh *ssh) 1231{ 1232 debug3("PAM: opening session"); 1233 1234 expose_authinfo(__func__); 1235 1236 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1237 (const void *)&store_conv); 1238 if (sshpam_err != PAM_SUCCESS) 1239 fatal("PAM: failed to set PAM_CONV: %s", 1240 pam_strerror(sshpam_handle, sshpam_err)); 1241 sshpam_err = pam_open_session(sshpam_handle, 0); 1242 if (sshpam_err == PAM_SUCCESS) 1243 sshpam_session_open = 1; 1244 else { 1245 sshpam_session_open = 0; 1246 auth_restrict_session(ssh); 1247 error("PAM: pam_open_session(): %s", 1248 pam_strerror(sshpam_handle, sshpam_err)); 1249 } 1250 1251} 1252 1253int 1254is_pam_session_open(void) 1255{ 1256 return sshpam_session_open; 1257} 1258 1259/* 1260 * Set a PAM environment string. We need to do this so that the session 1261 * modules can handle things like Kerberos/GSI credentials that appear 1262 * during the ssh authentication process. 1263 */ 1264int 1265do_pam_putenv(const char *name, char *value) 1266{ 1267 int ret = 1; 1268#ifdef HAVE_PAM_PUTENV 1269 char *compound; 1270 size_t len; 1271 1272 len = strlen(name) + strlen(value) + 2; 1273 compound = xmalloc(len); 1274 1275 snprintf(compound, len, "%s=%s", name, value); 1276 ret = pam_putenv(sshpam_handle, compound); 1277 free(compound); 1278#endif 1279 1280 return (ret); 1281} 1282 1283char ** 1284fetch_pam_child_environment(void) 1285{ 1286 return sshpam_env; 1287} 1288 1289char ** 1290fetch_pam_environment(void) 1291{ 1292 return (pam_getenvlist(sshpam_handle)); 1293} 1294 1295void 1296free_pam_environment(char **env) 1297{ 1298 char **envp; 1299 1300 if (env == NULL) 1301 return; 1302 1303 for (envp = env; *envp; envp++) 1304 free(*envp); 1305 free(env); 1306} 1307 1308/* 1309 * "Blind" conversation function for password authentication. Assumes that 1310 * echo-off prompts are for the password and stores messages for later 1311 * display. 1312 */ 1313static int 1314sshpam_passwd_conv(int n, sshpam_const struct pam_message **msg, 1315 struct pam_response **resp, void *data) 1316{ 1317 struct pam_response *reply; 1318 int r, i; 1319 size_t len; 1320 1321 debug3("PAM: %s called with %d messages", __func__, n); 1322 1323 *resp = NULL; 1324 1325 if (n <= 0 || n > PAM_MAX_NUM_MSG) 1326 return (PAM_CONV_ERR); 1327 1328 if ((reply = calloc(n, sizeof(*reply))) == NULL) 1329 return (PAM_CONV_ERR); 1330 1331 for (i = 0; i < n; ++i) { 1332 switch (PAM_MSG_MEMBER(msg, i, msg_style)) { 1333 case PAM_PROMPT_ECHO_OFF: 1334 if (sshpam_password == NULL) 1335 goto fail; 1336 if ((reply[i].resp = strdup(sshpam_password)) == NULL) 1337 goto fail; 1338 reply[i].resp_retcode = PAM_SUCCESS; 1339 break; 1340 case PAM_ERROR_MSG: 1341 case PAM_TEXT_INFO: 1342 len = strlen(PAM_MSG_MEMBER(msg, i, msg)); 1343 if (len > 0) { 1344 if ((r = sshbuf_putf(loginmsg, "%s\n", 1345 PAM_MSG_MEMBER(msg, i, msg))) != 0) 1346 fatal("%s: buffer error: %s", 1347 __func__, ssh_err(r)); 1348 } 1349 if ((reply[i].resp = strdup("")) == NULL) 1350 goto fail; 1351 reply[i].resp_retcode = PAM_SUCCESS; 1352 break; 1353 default: 1354 goto fail; 1355 } 1356 } 1357 *resp = reply; 1358 return (PAM_SUCCESS); 1359 1360 fail: 1361 for(i = 0; i < n; i++) { 1362 free(reply[i].resp); 1363 } 1364 free(reply); 1365 return (PAM_CONV_ERR); 1366} 1367 1368static struct pam_conv passwd_conv = { sshpam_passwd_conv, NULL }; 1369 1370/* 1371 * Attempt password authentication via PAM 1372 */ 1373int 1374sshpam_auth_passwd(Authctxt *authctxt, const char *password) 1375{ 1376 int flags = (options.permit_empty_passwd == 0 ? 1377 PAM_DISALLOW_NULL_AUTHTOK : 0); 1378 char *fake = NULL; 1379 1380 if (!options.use_pam || sshpam_handle == NULL) 1381 fatal("PAM: %s called when PAM disabled or failed to " 1382 "initialise.", __func__); 1383 1384 sshpam_password = password; 1385 sshpam_authctxt = authctxt; 1386 1387 /* 1388 * If the user logging in is invalid, or is root but is not permitted 1389 * by PermitRootLogin, use an invalid password to prevent leaking 1390 * information via timing (eg if the PAM config has a delay on fail). 1391 */ 1392 if (!authctxt->valid || (authctxt->pw->pw_uid == 0 && 1393 options.permit_root_login != PERMIT_YES)) 1394 sshpam_password = fake = fake_password(password); 1395 1396 sshpam_err = pam_set_item(sshpam_handle, PAM_CONV, 1397 (const void *)&passwd_conv); 1398 if (sshpam_err != PAM_SUCCESS) 1399 fatal("PAM: %s: failed to set PAM_CONV: %s", __func__, 1400 pam_strerror(sshpam_handle, sshpam_err)); 1401 1402 sshpam_err = pam_authenticate(sshpam_handle, flags); 1403 sshpam_password = NULL; 1404 free(fake); 1405 if (sshpam_err == PAM_MAXTRIES) 1406 sshpam_set_maxtries_reached(1); 1407 if (sshpam_err == PAM_SUCCESS && authctxt->valid) { 1408 debug("PAM: password authentication accepted for %.100s", 1409 authctxt->user); 1410 return 1; 1411 } else { 1412 debug("PAM: password authentication failed for %.100s: %s", 1413 authctxt->valid ? authctxt->user : "an illegal user", 1414 pam_strerror(sshpam_handle, sshpam_err)); 1415 return 0; 1416 } 1417} 1418 1419int 1420sshpam_get_maxtries_reached(void) 1421{ 1422 return sshpam_maxtries_reached; 1423} 1424 1425void 1426sshpam_set_maxtries_reached(int reached) 1427{ 1428 if (reached == 0 || sshpam_maxtries_reached) 1429 return; 1430 sshpam_maxtries_reached = 1; 1431 options.password_authentication = 0; 1432 options.kbd_interactive_authentication = 0; 1433} 1434#endif /* USE_PAM */ 1435