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